There uses to be direct buses to Leshan and Emeishan, later stoped. I have no idea if they are still in service now. You can ask the staff in Chengdou Airport when you get there. Or you can take airport bus to Minshan Hotel. Thent ake a taxi to Xinnanmen Bus Station, which is the tourist bus center of the city. There are buses to both Emeishan and Leshan.