Does the subject want to ask "how many kilometers is it from Lhasa to Chengdu by National Highway 3 17"? 2487 kilometers. According to Baidu map, it takes 37 hours and 34 minutes to drive from Lhasa to Chengdu and take the Sichuan-Tibet Line 3 17 National Highway. The actual highway mileage is 2,487 kilometers.