SqlParameter[] conditionParameter = new SqlParameter[]
        {        
           new  SqlParameter("@Year",ddlYear.SelectedValue)
        };

        ReportParameter[] param = new ReportParameter[]
        {
            new ReportParameter("ReportParameterYear", ddlYears.SelectedItem.Text.ToString()),
        };

        //Get Data into dataset
        string thisConnectionString = ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString;
        SqlConnection thisConnection = new SqlConnection(thisConnectionString);
        DataSet thisDataSet = new DataSet();
        thisDataSet = SqlHelper.ExecuteDataset(thisConnection, "uspXXX", conditionParameter);
        ReportDataSource datasource = new ReportDataSource("dsxxx_uspxxx", thisDataSet.Tables[0]);

        //Displayed in ReportVierer
        ReportViewer1.Visible = true;
        ReportViewer1.LocalReport.DataSources.Clear();
        ReportViewer1.LocalReport.DataSources.Add(datasource);

        if (thisDataSet.Tables[0].Rows.Count == 0)
        {
            lblMessage.Text = "xxxx!";
        }
        else
        {
            lblMessage.Text = String.Empty;
        }
        ReportViewer1.LocalReport.SetParameters(param);
        ReportViewer1.LocalReport.Refresh();
    }

------解决方案--------------------
先转换好了再给数据源啊