Seal formation on the soil surface during rainstorms reduces rain infiltration and leads to runoff and erosion. The objective of this study is to investigate the soil seal formation in different soils, and to analyze the chemical and physical processes in it. Experiments were conducted with four different soils with different Exchangeable Sodium Percentage(ESP)(2, 5, 10 and 20) and different clay contents(10%, 20%, 40% and 60%) under rainfall simulation. The effects of ESP and clay content of soil on seal formation were discussed by means of shielding chemical and physical seal formation with spreading phosphogypsum(PG) (2000 kg/hm²) and PG plus (polyacrylamide) PAM(PG 2000 kg/hm²+ PAM 20 kg/hm²) on soil surface. In high ESP soils, chemical seal formation is predominated, and in low ESP soils, the physical seal formation take more shares. The physical seal formation is in low degree with low clay content soils, however, developed well in high clay content soils.