OK, I know how to fix the problem now.
The axis-remote error message:
no application named "axis"
comes from Tkinter's (Tk) "send" command which rely on X server to exchange message between two Tk's applications.
I got above error message because I run linuxcnc at DISPLAY localhost:11.0 and axis-remote at DISPLAY localhost:10.0. I use two terminals login to CNC host via "ssh -Y IP_of_my_CNC_host",
If I login via GUI and run linuxcnc and axis-remote both at DISPLAY :0, then axis-remote run perfectly.
If I use only one terminal login to CNC host via "ssh -Y ...". Run linuxcnc at background, "linuxcnc my.ini &" and then run "axis-remote" from the same terminal (DISPLAY :11.0), it's OK too.
Regards
KC