Affected by environment elements, the degeneration of mechanical property for ca r bon fiber reinforced polymer (CFRP) composites under hygrothermal environments i s an important engineering problem, and the key segment on solving this problem i s how to reappear the aging effect of natural environment on CFRP by taking acce lerated aging experiments under laboratory condition. Based on time-temperature-humidity superposition principle (TTHSP), the change of visco elasticity for CFRP is considered as damage measure for Hygrothermal aging. The equivalent convers ion relationship between different Hygrothermal environments is determined, and the calculating method of equivalent conversion coefficient is provided. Takin g a typical CFRP used in warcraft structure for example , equivalent conversion co efficients under different hygrothermal environments are calculated, the accel e rated aging environment spectrum are programmed according to the conversion of ground parking environment spectrum, and the accelerating result is acceptable . Finally, the influences of temperature and humidity on equivalent conversion c oefficient are checked, and the result shows that the influence of temperature c ha nge on equivalent conversion coefficient is more remarkable than that of humidi ty change.