How can I travel from jiuzaigou to Bi Pinggou .

I didn't find any bus. You can firstly take a bus at Jiuzhaigou Coach Station to Zhenjiangguan Railway Station, where you can take a bullet train to Chengdu East Railway Station. Then take Chengdu metro line 2 to Chadianzi Coach Station and take a coach to Lixian, where you can then take a taxi to Bipenggou. It's a detour. But it seems there is no other way.

Or try to hire a private car from Jiuzhaigou or Zhenjiangguan to Bipenggou, which will cost a lot of course.