The precipitation data from AIRS3STM inverted by AIRS detector on NASA's Aqua satellite was adopted to analyze the spatio-temporal distribution and variations of available precipitation in China from 2003 to 2021. Linear fitting, Mann-Kendall test and empirical orthogonal function analysis were employed to reveal the influencing factors of spatio-temporal change. Results reveal that 1) interannual available precipitation during daytime and nighttime in China has been increasing with daytime rising rate of 0.044 kg·m^-2·a^-1 and nocturnal rising rate of 0.062 kg·m^-2·a^-1. Daytime mutation point occurred in 2014 while nocturnal mutation point occurred in 2008. 2) Changes in all four seasons during day and night show upward trends with summer change rate being highest while change rate in spring and winter is low. Only changes in summer daytime, summer, autumn and winter nighttime passed significance test of α=0.05. 3) Spatial distribution of daytime available precipitation and surface temperature in China is negatively correlated with latitude. Lower latitude sees higher available precipitation and surface temperature. South China has larger available precipitation than northwest China. EOF analysis on some typical areas also verifies this law. 4) Amount of available precipitation is positively correlated with surface temperature and such trend grows more obvious with higher surface temperature.