If I stay in Shanghai and need go to Jiashan by car, which location stay in shanghai will be best?

Well, you can stay near People's Square, where many hotels are available and the traffic situation is also good.
Hotels like Jinjiang Metropolo Hotel Classiq in 123 South Xizang Rd, Hi Inn Hotel in 66 Lane, Middle Xizang Rd, and Shaani Inn in 17 South Yunnan Rd are good choices.