> >> Could you pleas show the output of the two commands in a cmd.exe
> >> window?
> >> With and without the "&& exit || exit" tail.
> >
> > For command with `-l username`, the output is ` username@192.168.x.x's
> password:`.
> > For command without `-l username` the output is ` login as:`.
> >
> > It is the same with or without the "&& exit || exit" tail.
> 
> Thanks, this looks proper. Could you please call Emacs like "emacs -Q --eval
> '(setq tramp-verbose 10)'"? Try to connect via plink. If it hangs or runs into
> the timeout, send the resulting Tramp debug buffer "*debug tramp/plink
> 192.168.x.x*" or "*debug tramp/plink username@192.168.x.x*".

Please find the attachment. I have deleted some repeated part to reduce the file size.

> 
> Best regards, Michael.

Best Regards,
Shuguang