I an canadian and travelling to Nepal via two cities in china

Hi
I am canadian and want to travel to Nepal. My schedule is Vancouver to guanzao and transiting for 15 hrs then from there to nanjing and lay over for 2 hours and then to kathmandu. So I have two transits in china. Do I need visa to stay there ? Though my stay in china is less than 24 hrs I have transit in two cities. Please help me with this
Thank you