The influence of different soy protein spray coating dispersion concentrations and spraying conditions on the atomization angle and the atomization overall morphology was studied to evaluate spraying quality on vegetable composite paper. The high-speed camera was used to collect images of spraying and then the spray angle was calculated through the image processing function of Matlab software. The effect of the concentration and process parameters on spray angle was also analyzed according to the response surface methodology. When the hydraulic pressure was high and the air pressure was low, poor atomization was generated. With the increase of air pressure, the better atomization performance was achieved. In the aspect of single factor, concentration and air pressure had a significant effect on the spray angle. The relative model of spray angle， process parameters and concentration was established by analytical software. The optimal spraying condition was obtained as follows. The spray angle of SPSCD was up to 81.4690° , when the concentration of SPSCD was 11.13%， the air pressure was 2 MPa, and the hydraulic pressure was 1.64 MPa.