In order to reveal the contribution of colloidal phosphorus to the loss of total phosphorus, we carried out a field experiment to collect the water of paddy surface and ditches under typical rainfall events. According to the actual weather conditions, we selected a typical rainstorm event (48 mm/h) and eight rainfall events with different intensities of 8, 9, 19, 23, 23, 32, 36, and 49 mm/h. The results showed that:(1) Phosphorus loss in the surface water and paddy field drainage was mainly composed of particle phosphorus. In the total phosphorus passed over the 1 μm filter, the loss of colloidal phosphorus accounted for 21%~73%, even exceeding the loss contribution of true dissolved phosphorus. (2) The contribution of colloidal phosphorus in the surface water after rainfall was 9%~44%, and the contribution of colloidal phosphorus loss in paddy field drainage was 10%~16%. There was positively correlation among metal oxide colloid, organic colloid, metal oxide-organic colloid and colloidal phosphorus loss contribution. The correlation coefficients in the surface water were 0.544, 0.635, 0.781 (p<0.05), and the corresponding values in the drainage in the paddy field were 0.734, 0.350, 0.747 (p<0.05), respectively. They were the important forms of colloidal phosphorus in runoff. (3) Fertilization reduced the contribution of colloidal phosphorus loss by affecting conductivity and ionic strength, while rainfall intensity increased the contribution of colloidal phosphorus loss by affecting pH value. The R² value of linear regression coefficient of rainfall intensity and colloidol phosphorus concentration of drainage in the paddy field was 0.75, but the degree of influence on the loss of colloidal phosphorus in the surface water and rice field drainage was different.