只需将字符串转换为 [xml] 即可读取 XML:

You can read XML simply by casting a string to [xml]:

$xml = [xml](Get-Content foo.xml)

然后你就可以使用

$xml.ValCurs.Valute | Where-Object {$_.ID -eq 826} | Select-Object Nominal,Value

或更短:

$xml.ValCurs.Valute | ? {$_.ID -eq 826} | select Nominal,Value