已解决。代码修改为：
sql="select * from  B3J where bianhao='"&nowbianhao&"' and zu=false"
      set rs_shulian=conn.execute(sql)
      nowjggr=0
      nowpggr=0
      do while rs_shulian.eof=false
        nowjggr=nowjggr+rs_shulian("jggr")
        nowpggr=nowpggr+rs_shulian("pggr")
        rs_shulian.movenext
      loop
set rs2=server.createobject("ADODB.RecordSet")
sql="select * from B3J where bianhao='"&nowbianhao&"'"
rs2.open sql,conn,1,3
do while rs2.eof=false
rs2.addnew
rs2("bianhao")=nowbianhao
rs2("title")="总计[工日小计+工日小计×工日系数"&nowgrxs&"]"
rs2("jggr")=nowjggr
rs2("pggr")=nowpggr
rs2("zu")=true
rs2.movenext
loop

但是有一点我不明白，为什么用一开始的代码就取不到汇总值，其实后一种写法我也是猜测性尝试下的，没有想到有效果