29.6 kilometers. According to the Baidu map, it is 29.6 kilometers from Deyang Zhongjiang to Longtai Shuxiangmen, which takes 8 minutes. The bus route is as follows:

1. First, get on the bus from Zhongjiang Cangshan Station and take the bus to Longtai Town.

2. The second route is 29.6 kilometers, and it takes 8 minutes to drive. After Cangshan, Yuxing and Yong 'an stations, get off at Longtai Town Station.

3. Finally, it takes 29.6 kilometers to drive from Zhongjiang to Longtai Town, which can be reached in 6 minutes.