Can I know is there anyone know how to statup AIX in GUI and text mode?
Thank You.....
You probably mean by GUI mode the dtlogin interface ? if so, it is usually launch at startup by /etc/rc.dt
Grep that line in /etc/inittab (where most of aix's startup scripts is launched) and comment it out
Generally you'll have something like this
aix# grep /etc/rc.dt /etc/inittab
dt:2:wait:/etc/rc.dt
aix#
That was just a theory so proceed with care 
look up the dtconfig command. i THINK 'dtconfig -e' may do it.