On the basic of impact tests, we analysed the Load-Deflection information of the molded pulp products in the impact height of 30cm, 50cm, 80cm and under the relative humidity of 50%,65%,80%,90%. Meanwhile the nominal stress-strains curves and the energy absorption curves were established. The experimental results show that: under a certain impact height, with the increase of relative humidity, the nominal stress-strain curves move to the downward, the elasticity modulus and buckling critical stress decrease, and the best energy absorption point offset to the lower left. When the RH increase from 50% to 65%, 80% and 90%, the average second buckling critical stress is 14%,24% and 42% decreased respectively. Under a certain RH, with the increase of impact height, the nominal stress-strain curves move to the upward, the elasticity modulus and buckling critical stress decrease, and the best energy absorption point offset to the upper right, and this effect significantly enhanced with the increase of RH. Under impact load, the molded products occur two obvious buckling.