Abstract: In the hot water of 40℃, 60℃, 80℃ and 100℃, the hot water aging of Bayer-PC, Japan-PC and Korea-PC was investigated. The number of samples is 9 in the aging time of 0~200 h. The law of water absorption in the process of hot water aging and the effects of different hot water aging conditions on the surface fracture appearances of PCs were studied. The hot water aging mechanism of PCs was discussed. The results show: (1) with increasing of time and temperature, the moisture content increases and goes a equilibrium value; (2) the number of microcavities increases progressively with the time and temperature; (3) because of the hydrolysis of PCs, the theoretical values of equilibrium moisture M_m and diffusivity D_x are higher than the experimental values.