If i am flying standby with my mom who is a working crew member. what can i show for documentation

I think you can ask your mother's company to issue you a guarantee letter as the proof for your round-trip tickets. In addition, if you travel to China for touristic purposes, you need to provide your passport, a photocopy of your passport, a filled-out application form, a bare-headed photo against white background, and a copy of hotel booking records.