1、这个判断进入执行了没有？

If app.Selection.Find.Execute("[编号]") Then \'查找到指定字符串

    msgbox(123)
    app.Selection.Text ="" &r("工号") & "-" &r("姓名") & "" \'此处只能用第一条记录的工号和姓名替换字符串[编号]

    msgbox(app.Selection.Text_
End If

2、你的页眉怎么设计的？截图贴出来。

你代码本身就是没问题的。没做任何修改。

\'批量生成多个word报表
Dim tm As String  = ProjectPath & "Attachments\\员工资料.doc" \'指定模板文件
\'批量修改页眉
Dim t As Table = Tables("员工资料")
For i As Integer = t.TopPosition To t.BottomPosition
    Dim r As Row = t.Rows(i)
    Dim fl As String = ProjectPath & "Reports\\" & r("工号") & r("姓名") & ".doc" \'指定目标文件
   
    Dim wrt As New WordReport(t,tm,fl) \'定义一个WordReport
    wrt.Buildone(r) \'逐行生成报表
    wrt.quit
   
    Dim app As New MSWord.Application
    try
        \'Dim fileName = ProjectPath & "Reports\\" & Tables("员工资料").current("编号") & " " & Tables("T").current("名称") & ".Doc"
        \'Dim fileName = ProjectPath & "Reports\\" & "员工资料.Doc"
       
        Dim doc As Object = app.Documents.Open(fl) \'测试可以打开每个文件
       
        app.ActiveWindow.ActivePane.View.SeekView = MSWord.WdSeekView.wdSeekCurrentPageHeader
        If app.Selection.Find.Execute("[编号]") Then \'查找到指定字符串
            app.Selection.Text ="" &r("工号") & "-" &r("姓名") & ""   \'此处只能用第一条记录的工号和姓名替换字符串[编号]
            \'app.Selection.Text ="测试编号" \'替换字符串
        End If
        app.ActiveWindow.ActivePane.View.SeekView =  MSWord.WdSeekView.wdSeekMainDocument
       
        app.Visible = True
    catch ex As exception
        msgbox(ex.message)
        app.Quit
    finally
        \'app.Quit
    End try
Next

app.Visible = True

改成

doc.save

app.quit