Blast shock wave damage effects were analyzed and main influence parameters about light armored vehicle bottom damage effects against blast shock wave were identified, which based on damage rule was researched using numerical simulation method. Finite element models were built using non-linear dynamics software of AUTODYN. Influence rules about bottom armor damage effects affected by such key parameters as bottom armor thickness, material, construct and explosion distance were studied. Results show that the single metal structure in homogeneous armor protection has the best optimal performance and dural's protective performance is the worst. When the angle is 10 degrees, V armor structure comprehensive protective performance is the best. After installing mounted flat, anti-damage ability is stronger. Results can provide reference to light armored vehicle bottom defense and damage effectiveness assessment.