Abstract: When an urban rail rapid transit line undergoes downtown,train speed is limited due to the high density of stations,and technical scheme of Overhead Catenary System（OCS）and tunnel section is furthermore influenced. Since the underground interval of the first phase project of Chengdu Metro Line 13 has a speed limit of 100 km/h,considering the OCS and aerodynamic effect study,comprehensive economic and technical comparison among tunnel engineering,shield machine purchase and catenary engineering is conducted,and 140 km/h shield tunnel section and integral rigid and flexible suspension are adopted. Compared to the scheme that adopts 100 km/h shield tunnel section and rigid suspension, this scheme requires same level of investment while possesses technical advantages. The shield lining segment outer diameter in this scheme is 8300 mm,compatible with both Chengdu Metro Line 17 and 18 in the aspects of shield construction and precast segment. The scheme has been adopted in the preliminary design of Chengdu Metro Line 13 first phase project for guidance of engineering implementation.