thank you very very much, i have just connected the OEM.
but I have an another problem.
in my service manager, there are many oracle service, but I don't know what is this serive's use.
Some service is manual. Include:
OralceOraHome81Agent manual
OracleOraHome81ClientCache manual
OracleOraHome81dataGatherer manual
OracleOraHome81ManagementServer auto
OracleOraHome81TNSListener auto
OracleServiceORADB auto
Oracle WebAssistant0 auto

the service "OracleOraHome81ManagementServer" is auto.but when I start the OS(windwos2000), this service doesn't autostart. I check the log, have 3 useful messege.
1: The service is entering production run mode.
2:The service was started.
3:(this is an error) detail:"The service has terminated abnormally. See the file D:\Oracle\Ora81\sysman\log\OMS.log for details."
I think this is why I can't connect the OEM. When I start it manually, I connect the OEM normally.
please helps
thanks