From China to Hanoi, you have some routes. Each of them has their own advantages:
1. Kunming - Hekou - Lao Cai - Hanoi:
Chinese side has no train in this route. From Kunming to Hekou border gate, if you travel by bus, it will take almost 10 hours, including lunch time. From Hekou to Lao Cai town, it lasts 10 minutes by motorbike/taxi. The next step is to go to Lao Cai railway station and find a train ticket to Hanoi (overnight train). So, it is about 790 km (490km by bus and 300km by train) from Kunming to Hanoi.
2. Nanning - PingXiang - Lang Son - Hanoi:
By bus: Huu Nghi Quan (Friendship Pass) is about 17km from Lang Son town. It is wise to arrive at Friendship Pass (customs and immigration) before 4:30 PM, because they do not stamp foreign passports after that time. After that you can take a minibus tour to Hanoi. It costs VND 60,000 ($3) for this trip and it takes 3,5-4 hours.
By train: Beijing - Nanning – Hanoi trip takes you about 40 hours. You will need to change the train at Dong Dang border town, since the rail width in China is 1,4m, while in Vietnam it is only 1m.
3. Nanning - DongXing - MongCai - Ha Long - Hanoi:
There are direct buses from Nanning to Halong Bay, which start 8:00 am in the morning, from River South Bus Centre (Jiang Nan Ke Yun Zhong Xing). The bus passes the border at DongXing border town instead of Gate of Friendship. Total bus travel time from Nanning to Halong bay is 9 hours and it costs VND 3,000,000 ($150). You can also go by express boat from MongCai to Halong Bay then by bus to Hanoi, but it takes longer.
Related Readings:
Crossing the border between China and Vietnam
Vietnam Railway System
Tips for taking night train in Vietnam
