In order to improve the protection ability of light armored vehicle, based on the simplification of the vehicle body, numerical computation was carried out on the damage effect under the blast shock wave for five types of bottom plates V type, W type, wave type, boat type and plate-boat type. Taking pressure at the same location and displacement as parameters, anti-explosion ability of five types of bottom plates above was analyzed and compared. The plate-boat has the best anti-explosion ability, while it is not the optimal selection for light armored vehicle bottom. Considering vehicle body height and inner space, the boat type and V type are the optimal selection. The research result is significant to improve the bottom defense ability against blast shock wave.