一种简单的方法是用新行和11替换新行(由于 {:< 10}中的10，所以将其替换为11)，但您在格式中添加了一个额外的空格)空格:

An easy way to achieve this is replacing a new line with a new line and 11 (11 because of the 10 in {:<10} but you add an additional space in your format) spaces:

B2 = B.replace('\n','\n           ')
print('{:<10} {}'.format(A, B2))

或更优雅:

B2 = B.replace('\n','\n'+11*' ')
print('{:<10} {}'.format(A, B2))

在 python3 中运行它:

$ python3
Python 3.5.2 (default, Nov 17 2016, 17:05:23) 
[GCC 5.4.0 20160609] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> A = '[A]: '
>>> B = 'this is\na string\nwith a new line'
>>> B2 = B.replace('\n','\n           ')
>>> print('{:<10} {}'.format(A, B2))
[A]:       this is
           a string
           with a new line