This study was carried out to evaluate the changes in physicochemical properties of pitaya powder produced by spray-drying under the different temperature storage at 5-7 , room temperature, and 50  for 40 days, The results showed that delta E of color increased but the content of betacyanin and total phenolic decreased following temperature increase. The degradation of betacyanin and total phenolic content in all samples during storage fitted the first-order reaction. Moreover, the behavior of moisture content in pitaya powder under different relative humidity was investigated. The isotherm curve of pitaya powder was built (y = 3,2655e0,0106x). The result also showed the GAB equation can be used to calculate the M0 of the sample better than the BET equation.