Does Chengdu sightseeing bus to Research Base of Giant Panda Breeding still run?

No, it doesn't run these days. But you may take bus line 64 from Tianfu Square East Station, and get off at Middle Jingzhu Road West Station. Next, walk south for about 219 yards (200 meters) to the 3rd Ring Road Sichuan-Shaanxi Overpass South Station. Take bus line 87, 198, or 198a, and get off Panda Base Station.

Or, you may taxi there directly from Tianfu Square for CNY 40-50. The pandas are pretty cute! Have fun!