I am Nepalese passport holder. I am flying from Canada to Nepal.

Hi, I am flying from Vancouver Canada to kathmandu Nepal. My flight has 2 stops in China. first stop is in Nanjing for few hours. Arrives there at 2:45 pm on 11 Dec, 2017 and fly to Kunming at 4:25 Pm the same day and arrives at Kunming at 7:35 pm same day. From Kunming my departure to Kathmandu is at 3:25 pm on 12 Dec, 2017. (waiting time in Kunming is 19 h 50 min). but from first stop to departure is 24h 40 min. Do i need chinese visa in advance in this case??