测试结果：
VB.NET
Imports Spire.Pdf
Imports Spire.Pdf.Graphics
Imports Spire.Pdf.Lists
Imports System
Imports System.Drawing
Namespace List2
Class Program
Private Shared Sub Main(ByVal args As String())
Dim doc As PdfDocument = New PdfDocument()
Dim page As PdfPageBase = doc.Pages.Add(PdfPageSize.A4)
Dim y As Single = 10
Dim brush1 As PdfBrush = PdfBrushes.Black
Dim font1 As PdfTrueTypeFont = New PdfTrueTypeFont(New Font("宋体", 18F, FontStyle.Regular), True)
Dim format1 As PdfStringFormat = New PdfStringFormat(PdfTextAlignment.Center)
page.Canvas.DrawString("目录一览", font1, brush1, page.Canvas.ClientSize.Width / 2, y, format1)
y = y + font1.MeasureString("目录一览", format1).Height
y = y + 5
Dim rctg As RectangleF = New RectangleF(New PointF(0, 0), page.Canvas.ClientSize)
Dim brush As PdfLinearGradientBrush = New PdfLinearGradientBrush(rctg, Color.DarkBlue, Color.Brown, PdfLinearGradientMode.Vertical)
Dim font2 As PdfTrueTypeFont = New PdfTrueTypeFont(New Font("宋体", 15F, FontStyle.Regular), True)
Dim formatted1 As String = "第一章 总 论"
Dim formatted2 As String = "第一节 经济法概述 "
Dim formatted3 As String = "第二节 经济法主体 "
Dim formatted4 As String = "第二章 公司法律制度"
Dim marker1 As PdfOrderedMarker = New PdfOrderedMarker(PdfNumberStyle.Numeric, NewPdfFont(PdfFontFamily.Helvetica, 15F))
Dim marker2 As PdfOrderedMarker = New PdfOrderedMarker(PdfNumberStyle.LowerRoman, NewPdfFont(PdfFontFamily.Helvetica, 12F))
Dim list1 As PdfSortedList = New PdfSortedList(font2)
list1.Indent = 0
list1.TextIndent = 5
list1.Brush = brush
list1.Marker = marker1
Dim list2 As PdfSortedList = New PdfSortedList(font2)
list2.Marker = marker2
list2.Brush = brush
list2.TextIndent = 10
Dim item As PdfListItem = list1.Items.Add(formatted1)
item.SubList = list2
list2.Items.Add(formatted2)
list2.Items.Add(formatted3)
list1.Items.Add(formatted4)
Dim textLayout As PdfTextLayout = New PdfTextLayout()
textLayout.Break = PdfLayoutBreakType.FitPage
textLayout.Layout = PdfLayoutType.Paginate
list1.Draw(page, New PointF(0, y), textLayout)
doc.SaveToFile("多级列表.pdf")
System.Diagnostics.Process.Start("多级列表.pdf")