Hello bprego：）

Sorry but in the nested GridView's DataSource you should say "DepartNames" instead of "DeptName"……；Well，plz attention to my complete codes——

【cs code-behind】

protected void Page_Load(object sender, EventArgs e)
{
    string filePath3 = Server.MapPath("App_Data/test.xml");
    var result = from f in XDocument.Load(filePath3).Descendants("Floor")
    select new
        {
            FloorName = f.Value,
            DepartNames = from g in f.Descendants("DeptName")
            select g.Value
        };
}

【aspx codes】

<asp:GridView ID="GridView3" runat="server" AutoGenerateColumns="False" 
        Enabled="true" Visible="true" GridLines="None" 
        HorizontalAlign="Center" Width="100%" CellPadding="5" CellSpacing="1"> 
        <RowStyle Font-Size="X-Large" HorizontalAlign="Center" BackColor="#3E3E3D" ForeColor="White" />
        <AlternatingRowStyle BackColor="White" ForeColor="Black" /> 
        <HeaderStyle Font-Bold="True" Font-Size="XX-Large" BackColor="#D7AD3B" />
        <Columns>
            <asp:TemplateField HeaderText="Floor">
                <ItemTemplate><%#Eval("Floor")%></ItemTemplate>
            </asp:TemplateField>
            <asp:TemplateField HeaderText="Department">
                <ItemTemplate>
                    <div>
                    <asp:GridView id="GridView4" runat="server" AutoGenerateColumns="false"
                    DataSource='<%#Eval("DepartNames")%>' >
                    <Columns> 
                        <asp:TemplateField HeaderText="Department"> 
                            <ItemTemplate> <%#Container.DataItem.ToString()%> </ItemTemplate> 
                        </asp:TemplateField> 
                    </Columns> 
                    </asp:GridView>
                    </div>
                </ItemTemplate>
             </asp:TemplateField>
        </Columns>
    </asp:GridView>