I'm a Bangladeshi. I have return trip like Dhaka->Kunming->Xi'an Xianyang->Nagoya. Do I need a visa?

Hi I am a Bangladeshi, working as a Professor of Shizuoka University. I bought an online ticket of China Eastern which has the flight like: Nagoya -> Shanghai Hongqiao -> Kunming -> Dhaka;
Return: Dhaka -> Kunming -> Xi an Xianyang -> Nagoya.