hi Joan Xie,
Thanks for the reply.
That did not work me on target. but yes it worked when I did below steps.
1. kept the .ttf(fonts files) in a foder and
2. used the command below before running the app
export QT_QPA_FOTNDIR="folder/path/of/your/fonts"
its worked ok now for my hmi.
Regards,
Lavakumar S