I'll be traveling in Thailand and Laos in May and was hoping to find a reliable bus/train route from Laos to Kunming.

If anybody has any information or advise let me know.

Thanks so much!

Yes, take the 8.30am bus from Luang Prabang north to Luang Nam Tha. The bus is comfortable and the road is good. Stay overnight in Luang Nam Tha and go to the bus station 10kms out of town and catch the 8.00am bus to the Laos/Yunnan border. Bus is smaller, and again the road is good. Hour and a half to the border, I think. The bus crosses the border and continues to Mengla. Change buses for a minibus that'll take you all the way to Jinghong. Stay overnight and take the Kunming bus the next day. Good luck.

I saw there is a direct bus from Viantiane to Kunming,you can check with the main bus station in Viantiane too.