Mike，你的思路是对的，但是你没有在时间不变的情况下保持当前颜色可用于后面的行。请注意颜色数组的用法。使用数组，你可以通过数字索引（代码中的'ColorIndex'）轻松访问元素。

Private Sub CommandButton1_Click()
    Dim ws As Worksheet
    Set ws = Worksheets(1)
    
    'Dim c As Long
    Dim CurrRow As Long     'The row we are currently evaluating
    Dim PrevRow As Long     'The previous row (act. first of current time)
    Dim CurrColor As Long   'The color index currently in use
    Dim ColorArr As Variant 'Array of colors
    Dim ColorIndex As Integer
    
    Dim Color0 As Long
    Dim Color1 As Long
    Dim Color2 As Long
    Dim Color3 As Long
    Dim Color4 As Long
    Dim Color5 As Long
    Dim Color6 As Long
    Dim Color7 As Long
    
    'Define the colors
    Color0 = RGB(142, 169, 219)
    Color1 = RGB(213, 184, 234)
    Color2 = RGB(255, 217, 102)
    Color3 = RGB(169, 208, 142)
    Color4 = RGB(244, 176, 132)
    Color5 = RGB(180, 238, 210)
    Color6 = RGB(208, 215, 145)
    Color7 = RGB(167, 127, 225)
    
    'Define an array of those colors
    ColorArr = Array(Color0, Color1, Color2, Color3, Color4, Color5, Color6, Color7)
    
    'Initial index that we will use
    ColorIndex = 0
    
    'Test of the color ?
    ws.Range("C9").Interior.Color = ColorArr(ColorIndex)
    
    Dim pr As Long
    Dim tms As Range
    
    pr = 0
    pr = ActiveSheet.Range("B15", ActiveSheet.Cells(Rows.Count, "B").End(xlUp)).Count
    Set tms = Application.Range("B15:B" & 14 + pr)
    
    Dim First As Integer
    Dim Last As Integer
    
    First = 15
    Last = 15 + pr - 1
    
    Debug.Print First
    Debug.Print Last
    
    
    'Traverse the cells with the time stamps
    'Color the first cell with the initial fill color
    'Following cells are colored with the same color ...
    '... if the time in cell is the same as previous
    'If the time in the cell is different ...
    '  - update PrewRow to the current
    '  - update ColorIndex
    'Finally, fill cell
    '
    PrevRow = First
    For CurrRow = First To Last
        If CurrRow = First Then
            Cells(CurrRow, 2).Interior.Color = ColorArr(ColorIndex)
        Else

            'Check if time is different from previous
            If Cells(CurrRow, 2).Value <> Cells(PrevRow, 2).Value Then
                PrevRow = CurrRow
                ColorIndex = ColorIndex + 1
            End If

            'Fill cell
            Cells(CurrRow, 2).Interior.Color = ColorArr(ColorIndex)
        End If
    Next
    
End Sub