Getting to Xinnanmen bus station, or chadianzi bus station from Chengdu railway station

To Chadianzi Bus Station: Take the subway line 1 to Tianfu Square, where you can transfer to line 2 to the Chadianzi bus station directly. Take the Exit D. The travel time is about 35 mins.

To Xinnanmen Bus Station: In the railway station east bus stop, you can take the bus No. 28 to Xinnan Road. Then walk about 140 yards, you will reach the Xinnanmen Bus Station. The travel time is about 20 mins.

You arrive at the train station still early, so you can surely catch a bus to Jiuzhaigou on the same day if you book the bus tickets in advance.

Well, in travel peak season, you can book the tickets about 15 days in advance. But the official website only has Chinese version. you may ask help from your Chinese friends for the booking.