更新：
时，由于发布的的Windows Phone 8.1 ，就可以了，甚至在应用层面通过将覆盖主题设置的 RequestedTheme 上的任何控件属性在设置用户

Update : Since the release of Windows Phone 8.1, you can set the RequestedTheme attribute on any control, or even at the app level to override the Theme set by the users in the Settings.

例，迫使光主题：的

Example to force the Light theme:

的在代码的，App类的构造函数中：

In code, within the constructor of the App class :

/// <summary>
/// Provides application-specific behavior to supplement the default Application class.
/// </summary>
public sealed partial class App : Application
{
    private TransitionCollection transitions;

    /// <summary>
    /// Initializes the singleton application object.  This is the first line of authored code
    /// executed, and as such is the logical equivalent of main() or WinMain().
    /// </summary>
    public App()
    {
        this.RequestedTheme = ApplicationTheme.Light;

        this.InitializeComponent();
        this.Suspending += this.OnSuspending;
    }
}

或在XAML 的：

<Application
    x:Class="App26.App"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    RequestedTheme="Light"
    xmlns:local="using:App26">
</Application>

对于旧的的Windows Phone 8 应用模式：

当然，在设计准则使用的主题资源来确保您的应用程序适用于任何主题色和强调色推荐。

It is of course recommended in the design guidelines to use the theme resources to make sure your app works with any theme and accent color.

不过，如果你真的想迫使黑暗的主题，这里是由鲁迪Huyn在他的博客提供了一个解决方案：的 http://www.rudyhuyn.com/blog/2013/01/18/forcer-un-theme -sous窗口电话-8 /

However if you really want to force the dark theme, here is a solution provided by Rudy Huyn on his blog: http://www.rudyhuyn.com/blog/2013/01/18/forcer-un-theme-sous-windows-phone-8/

这样做是为了增加在App类中的方法，将覆盖所有的系统用画笔的颜色黑暗主题：

The idea is to add a method in your App class that will override all the system brushes with the colors of the dark theme:

private void DarkTheme()
{
    ((SolidColorBrush)Resources["PhoneRadioCheckBoxCheckBrush"]).Color = ((SolidColorBrush)Resources["PhoneRadioCheckBoxBorderBrush"]).Color = ((SolidColorBrush)Resources["PhoneForegroundBrush"]).Color = Color.FromArgb(0xFF, 0xFF, 0xFF, 0xFF);
    ((SolidColorBrush)Resources["PhoneBackgroundBrush"]).Color = Color.FromArgb(0xFF, 0x00, 0x00, 0x00);
    ((SolidColorBrush)Resources["PhoneContrastForegroundBrush"]).Color = Color.FromArgb(0xFF, 0x00, 0x00, 0x00);
    ((SolidColorBrush)Resources["PhoneContrastBackgroundBrush"]).Color = Color.FromArgb(0xFF, 0xFF, 0xFF, 0xFF);
    ((SolidColorBrush)Resources["PhoneDisabledBrush"]).Color = Color.FromArgb(0x66, 0xFF, 0xFF, 0xFF);
    ((SolidColorBrush)Resources["PhoneProgressBarBackgroundBrush"]).Color = Color.FromArgb(0x19, 0xFF, 0xFF, 0xFF);
    ((SolidColorBrush)Resources["PhoneTextCaretBrush"]).Color = Color.FromArgb(0xFF, 0x00, 0x00, 0x00);
    ((SolidColorBrush)Resources["PhoneTextBoxBrush"]).Color = Color.FromArgb(0xBF, 0xFF, 0xFF, 0xFF);
    ((SolidColorBrush)Resources["PhoneTextBoxForegroundBrush"]).Color = Color.FromArgb(0xFF, 0x00, 0x00, 0x00);
    ((SolidColorBrush)Resources["PhoneTextBoxEditBackgroundBrush"]).Color = Color.FromArgb(0xFF, 0xFF, 0xFF, 0xFF);
    ((SolidColorBrush)Resources["PhoneTextBoxReadOnlyBrush"]).Color = Color.FromArgb(0x77, 0x00, 0x00, 0x00);
    ((SolidColorBrush)Resources["PhoneSubtleBrush"]).Color = Color.FromArgb(0x99, 0xFF, 0xFF, 0xFF);
    ((SolidColorBrush)Resources["PhoneTextBoxSelectionForegroundBrush"]).Color = Color.FromArgb(0xFF, 0xFF, 0xFF, 0xFF);
    ((SolidColorBrush)Resources["PhoneButtonBasePressedForegroundBrush"]).Color = Color.FromArgb(0xFF, 0xFF, 0xFF, 0xFF);
    ((SolidColorBrush)Resources["PhoneTextHighContrastBrush"]).Color = Color.FromArgb(0xFF, 0xFF, 0xFF, 0xFF);
    ((SolidColorBrush)Resources["PhoneTextMidContrastBrush"]).Color = Color.FromArgb(0x99, 0xFF, 0xFF, 0xFF);
    ((SolidColorBrush)Resources["PhoneTextLowContrastBrush"]).Color = Color.FromArgb(0x73, 0xFF, 0xFF, 0xFF);
    ((SolidColorBrush)Resources["PhoneSemitransparentBrush"]).Color = Color.FromArgb(0xAA, 0x00, 0x00, 0x00);
    ((SolidColorBrush)Resources["PhoneChromeBrush"]).Color = Color.FromArgb(0xFF, 0x1F, 0x1F, 0x1F);

    ((SolidColorBrush)Resources["PhoneInactiveBrush"]).Color = Color.FromArgb(0x33, 0xFF, 0xFF, 0xFF);
    ((SolidColorBrush)Resources["PhoneInverseInactiveBrush"]).Color = Color.FromArgb(0xFF, 0xCC, 0xCC, 0xCC);
    ((SolidColorBrush)Resources["PhoneInverseBackgroundBrush"]).Color = Color.FromArgb(0xFF, 0xFF, 0xFF, 0xFF);
    ((SolidColorBrush)Resources["PhoneBorderBrush"]).Color = Color.FromArgb(0xBF, 0xFF, 0xFF, 0xFF);
}

然后，在App构造函数中，检查灯光主题是否启用，如果是，你重写主题：

Then, in the App constructor, you check whether the Light theme is enabled, and if it is, you override the theme:

if ((Visibility) Resources["PhoneLightThemeVisibility"] == Visibility.Visible)
{
    DarkTheme();
}