您需要在第一步中获取子文件夹并在其中搜索XML文件，例如：

# Get list of subfolders

$folders = get-childitem -Path [path] -Directory

# Get xml files in subdirectories

$xmlFiles = get-childitem -Path $folders.fullname -Filter '*.xml' -File -recurse

在搜索这个问题的答案时，我想出了一种实现所需功能的方法，方法是将多个调用的结果组合到Get-ChildItem：

# Find the list of all files and folders, including files in sub folders, from a directory:

$All = Get-ChildItem -Recurse

# Find a list of items to exclude from the first list:

$Exclude = Get-ChildItem *.xml

# Remove excluded items from the list of all items:

$Result = $All | Where-Object {$Exclude.FullName -NotContains $_.FullName}

# These terms can be combined into a single difficult-to-read statement:

Get-ChildItem -Recurse | Where-Object {(Get-ChildItem *.xml).FullName -NotContains $_.FullName}