一个选项是使用[String]的Split方法

"(3)_(9)--(11).(FT-2)".Split('()')

另一个选项是匹配除(和)之外的所有内容
作为正则表达式，它将执行[^()]+
故障

"[^()]" ' Match any single character NOT present in the list “()”
   "+"  ' Between one and unlimited times, as many times as possible, giving back as needed (greedy)

您可以使用以下代码块提取所有匹配项

Try
    Dim RegexObj As New Regex("[^()]+", RegexOptions.IgnoreCase)
    Dim MatchResults As Match = RegexObj.Match(SubjectString)
    While MatchResults.Success
        ' matched text: MatchResults.Value
        ' match start: MatchResults.Index
        ' match length: MatchResults.Length
        MatchResults = MatchResults.NextMatch()
    End While
Catch ex As ArgumentException
    'Syntax error in the regular expression
End Try

这应该可行：

Dim input As String = "(3)_(9)--(11).(FT-2)"
Dim searchPattern As String = "\((?<keep>[^)]+)\)|(?<=\))(?<keep>[^()]+)"
Dim replacementPattern As String = "${keep}" + Environment.NewLine
Dim output As String = RegEx.Replace(input, searchPattern, replacementPattern)

最简单的方法是使用Regex.Split（公式化为一个小控制台测试）：

Dim input = {"(3)_(9)--(11).(FT-2)", "(10)--(20).(10)/test--(99)"}
For Each s As String In input
    Dim parts = Regex.Split(s, "\(|\)")

    Console.WriteLine($"Input = {s}")
    For Each p As String In parts
        Console.WriteLine(p)
    Next
Next
Console.ReadKey()

基本上，我们有一行代码用于regex部分。
正则表达式\(|\)表示：在(或)处拆分，其中大括号使用\转义，因为它们在正则表达式中具有特殊含义。
稍短的正则表达式[()]（其中所需的字符包含在[]中）将产生相同的结果。