The running tunnel between Huaxin Street and Guanyinqiao on No. 3 line of Chongqing MRT system is constructed by extrashallow covered mining method. Due to the weak ground at the tunnel crown, the construction of the tunnel is difficult and full of risks. The characteristics of the project are presented and the construction scheme is analyzed in the paper. Key construction technologies, including double side drift method, road header excavation assisted by labor excavation, doublepipe nonshrinkage cementsodium WSS grouting and technology of side wall lining followed by arch lining, are applied in the running tunnel construction. These technologies can provide reference for the construction of similar urban underground works in the future.