你可以使用VB.Net中的ADO.NET库来连接和操作Microsoft Access数据库。以下是一个示例代码，用于循环遍历所有表单并将其导出为文本：

Imports System.Data.OleDb
Imports System.IO

Public Class Form1
    Private Sub btnExport_Click(sender As Object, e As EventArgs) Handles btnExport.Click
        ' 连接到Access数据库
        Dim connString As String = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=C:\path\to\your\access\database.accdb"
        Using conn As New OleDbConnection(connString)
            conn.Open()

            ' 获取所有表单的名称
            Dim dt As DataTable = conn.GetSchema("Tables")
            Dim tableNames As New List(Of String)
            For Each row As DataRow In dt.Rows
                Dim tableName As String = row("TABLE_NAME").ToString()
                If tableName.StartsWith("MSys") Then ' 排除系统表
                    Continue For
                End If
                tableNames.Add(tableName)
            Next

            ' 循环遍历每个表单并导出为文本
            For Each tableName As String In tableNames
                Dim sql As String = $"SELECT * FROM [{tableName}]"
                Using cmd As New OleDbCommand(sql, conn)
                    Using reader As OleDbDataReader = cmd.ExecuteReader()
                        ' 创建一个文件来保存导出的数据
                        Dim filePath As String = $"C:\path\to\exported\{tableName}.txt"
                        Using writer As New StreamWriter(filePath)
                            ' 写入表单的列名
                            For i As Integer = 0 To reader.FieldCount - 1
                                writer.Write(reader.GetName(i))
                                If i < reader.FieldCount - 1 Then
                                    writer.Write(vbTab) ' 使用制表符分隔列
                                End If
                            Next
                            writer.WriteLine()

                            ' 写入表单的数据行
                            While reader.Read()
                                For i As Integer = 0 To reader.FieldCount - 1
                                    writer.Write(reader(i))
                                    If i < reader.FieldCount - 1 Then
                                        writer.Write(vbTab)
                                    End If
                                Next
                                writer.WriteLine()
                            End While
                        End Using
                    End Using
                End Using
            Next

            conn.Close()
        End Using

        MessageBox.Show("导出完成！")
    End Sub
End Class

请确保将“C:\path\to\your\access\database.accdb”替换为你的Microsoft Access数据库的实际文件路径。导出的文件将保存在“C:\path\to\exported\”目录下，每个表单将作为一个单独的文本文件导出。