Regulation of automotive CO2 emission is becoming severe all over the world for a global warming counter measure. Car OEM needs not only an improvement of fuel economy of powertrain but also a reduction of automotive driving resistance. High expectation is held for thermoplastic fiber reinforced plastic (FRP) to automotive weight reduction at the point of productivity and recyclability. A thermoplastic FRP crash box has more energy absorption performance than the metal (steel, Aluminum, etc.) one. That is able to contribute to weight reduction and package improvement of automotive. However, stable load characteristic without regards to usage environment is required of automotive front bumper beam system . So it is necessary to consider the effect of temperature and resin degradation of thermoplastic. And in the case of discontinuous fiber FRP, a deviation of fiber orientation is generated in molding process. Through our research about a performance of thermoplastic FRP crash box, we acquired a knowledge to design a thermoplastic FRP crash box to keep its load characteristic stable under usage environment. We found that compression load characteristic of a thermoplastic FRP crash box in progressive crash mode in compression test has small temperature dependency, and to fulfill a condition that euler buckling load is larger than progressive crash load is necessary for stabilizing crash mode in compression test. In this paper, we show a design method of thermoplastic FRP crash box which uses two above-mentioned conditions in order to stabilize compression load characteristic to usage environment and fiber orientation effect.