In this paper, the crust structure of North-South Seismic Zone and its western side has been studied using long-period surface wave data. The results show that the crust in north and west parts is thicker than its south and east parts. Low-velocity zone exists within the crust of the whole area of North-South Seismic Zone and its western side. The average S-wave velocity is very low, about 3.37 km/s, and the velocity in the uppermost mantle is 4.40 km/s. It is possible that there is an uprising of mantle materials in the north section of North-South Seismic Zone and the thickness of lithosphere is only 60 km with a low-velocity zone in the bottom of the crust