Do I need Transit visa or anyother formal letter from Chinese ambassy hereby? Transit time 11 hours

I am a Nepalese citizen. I am going to Hanoi, Vietnam for official training through Guangzhou Baiyun ( CAN ) by China Southern airlines. My visa process is On- arrival. I have the Approval letter with Reference number and E- air ticket. so do I need Transit visa or anyother formal official letter from Chines ambassy herby ? Or are sufficient to show only the Approval letter and the E-air ticket ? Thank you.