Is it possible to leave Huanglong during evening?

If you want to leave at night, you need to hire a car in advance. And the ride from Huanglong to Songpan may cost you CNY200.

Many thanks!
You mean a car with a driver right?

We could also stay close to park and leave early in the morning.
Is it possible to sleep close to park?
Do you know if there are buses to Songpan in the morning?

Yes, I meant a car with a driver. You can stay near the park. The Seercuo International Hotel is highly recommended to you. It is located at Seercuo Village, near the entrance of the park. A standard room costs around CNY 600 per night. You can book a room by dialing 86-0837-8759222.

I heard that there are direct buses to Songpan from Huanglong. But I have no idea of its schedule. You can ask the staff at the bus station. Good luck! :)