Combining micro wet milling (MWM) and spray drying (SD) to powder white button mushroom (WBM) is a promising technique to give a higher quality product. The objectives were to determine the optimal number of passes in MWM process and to investigate the effect of different inlet temperatures in combination of MWM and SD process on the physical and chemical properties of WBM powders. The inlet temperature of SD was set to 160, 170, 180, 190 °C. The result showed 3 passes were sufficient to reduce the particle size and there was no significant difference between different inlet temperatures on physical properties of WBM powder, except for the color. MWM and SD process with inlet temperature 180 °C was proposed for powdering WBM.