My family is travelling by Air China (economy) from Kashgar to Chengdu and then Hong Kong.

I am afraid not. The lounge is for first class and business class passengers only. So, you may consider staying at Airport Juji Hotel at No. 2, North 2nd Road. It costs about CNY 80 per night. The hotel provides free pick up service. It is very convenient for you! Take some rest and wait the next flight. You can book a room by dialing at 86-028-85962954 .