Hello! Does Chinese resident permit help to get the Tibet permit?

I live in China and I have the residence permit. I was planning to travel to tibet and continue to Nepal for some trekking(Annapurna or so) but I am worried how can I reach Nepal from shanghai as I am going to chengdu and then to Tibet and Nepal. Is this possible or should I just fly from Chengdu to Nepal? My trip will take place on July.