From chengdu to emeishan. I plan to go emeishan on 6/1/16

Yes, one day for a round trip is doable. You should take the earliest train from Chengdu East which leaves at 07:30. You will reach EMS Station before 09:00. Then take a taxi to Baoguo Temple for a visit in around 10min at a cost of CNY15-20. Have a visit there and then transfer to a bus to Leidongping and take cable car onto the Golden Summit. The way back is the same and remember the last train back to Chengdu leaves at 21:40. Seize all your time!