The utility model discloses a prevent weighing down buffering knapsack device, include and set up out the receiving room that can open and close with the knapsack body, be equipped with the inside andoutside opening of intercommunication on the receiving room top, energy absorption area has been fixed a position to the receiving room through a limiting structure, the energy absorption area is including iterative first, two layers, this first layer, there are first connecting portion on second floor top relative extension the in addition, the second connecting portion, it is first, two connecting portion are furcately through the opening and outstanding knapsack is external, first connecting portion joinable safety vest, second connecting portion joinable safety hook, and when the user falls, it is first to make limiting structure release, two layers, make firstly, deviate from receiving room therefore buffering by the opening for two layers. In view of the above, make the utility model discloses the footpath have appearance good, accord with essence efficiency such as economic benefits.