First of all, I greatly thanks for your help.

There is still the error as before after I edited the Listener.ora on Standby Site. the following is its contents.
##############################
LISTENER =
(DESCRIPTION_LIST =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC0))
)
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = STBYSITE)(PORT = 1521))
)
)
(DESCRIPTION =
(PROTOCOL_STACK =
(PRESENTATION = GIOP)
(SESSION = RAW)
)
(ADDRESS = (PROTOCOL = TCP)(HOST = bjsmb01)(PORT = 2481))
)
)

SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(SID_NAME = PLSExtProc)
(ORACLE_HOME = E:\Oracle\Ora81)
(PROGRAM = extproc)
)
(SID_DESC =
(GLOBAL_DBNAME = A1NET)
(ORACLE_HOME = E:\Oracle\Ora81)
(SID_NAME = A1NET)
)
)
##############################

Some test like the following procedures are for you reference.
1. On Primary site, I created a Net Service Name which connects to Standby site with Net8 Configuration Assistant. The following error occured while proforming a test.
###################################
Connecting...ORA-01033: ORACLE initialization or shutdown in progress
The test did not succeed.

Some of the information you provided may be incorrect.
Press Back to review the information provided for net service name, or Change Login to change username.
###################################
2. On Primary site, when you execute the command:
c:> TNSPING STBY1 (which created on step 1)
the success info like this:
Attempting to contact (ADDRESS=(PROTOCOL=TCP)(PORT=1521)(HOST=stby1_ip)) OK (90 msec).

Looking forward to your expertises.

Mike