In order to study the agglomeration process of infant formula milk powder in the spray drying tower， single-factor experiments on the effects of inlet air temperature， spray lance angle， milk concentration and nozzle orifice diameter on the instant solubility and particle size distribution of infant formula were investigated， and response surface methodology based on Box-Behnken design was utilized to optimize the conditions of three main independent variables， including spray lance angle， milk concentration and nozzle orifice diameter for the dispersibility and 0~50 μm particles volume percentage of infant formula. The results showed that spray lance angle， nozzle orifice diameter and their interaction had significant effects， the optimum agglomeration process conditions were as follows： spray lance angle 11.4°， milk concentration 55%， nozzle orifice diameter 1.85 mm and inlet air temperature 180 ℃. Under these conditions， the dispersibility and 0~50 μm particles volume percentage of infant formula were 86.16% and 2.82%， respectively.