Flying Toronto-Beijing-Dhaka via Air Cda&China Estrn;must go through customs in Kunming. 72hr apply?

Do you mean your flight will fly from Beijing to Dhaka via Kunming? If so, the 72-hour free transit policy does not apply.

I am flying direct from Toronto to Beijing and would like to use the 72 hour exemption visa. Then I will fly to Dhaka. However, there is no direct international flight to Dhaka from Beijing on China Eastern so I must fly domestic to Kunming, get off the plane in Kunming, go through customs and then get right back on the same plane for an international flight to Dhaka.

Your are not eligible for 72 hours free transit because your flight stops in Beijing and Kunming.