手工从cmd命令行启动：
C:/Documents and Settings/wangnc>emctl start dbconsole
Environment variable ORACLE_SID not defined. Please define it.
设置Oracle_sid环境变量：
C:/Documents and Settings/wangnc>set oracle_sid=orcl
C:/Documents and Settings/wangnc>emctl start dbconsole
OC4J Configuration issue. C:/oracle/product/10.2.0/db_1/oc4j/j2ee/OC4J_DBConsole_sz-wangncD.cn.linecom.com_orcl not found.
还是不行，到目录 C:/oracle/product/10.2.0/db_1/oc4j/j2ee 下发现只有OC4J_DBConsole_localhost_orcl目录，并没有OC4J_DBConsole_sz-wangncD.cn.linecom.com_orcl这样的目录，然后设置oracle_hostname：
C:/Documents and Settings/wangnc>set oracle_hostname=localhost
C:/Documents and Settings/wangnc>emctl start dbconsole
问题解决