Based on the indoor model test, the head loss in the clear water filtration and optimal drainage time in the pollution state of the 80 mesh and 120 mesh self-cleaning screen filter was studied. The results showed that in the filtering state, general expression of clean water head loss was deduced through establishing Bernoulli equation from inlet to outlet of the filter. Two mesh head loss experience expression was obtained under different water flows (0～220m3/h). In the drainage conditions of two filters with five different discharge pressure differentials and three corresponding different sediment concentration, the rule of the curve showed that water sediment concentration of the drain changes with drainage time increasing at first and then decreasing. An inflection point appeared at 15s, and the outfall’s sediment tended to stabilization when the discharge time reached to 20s. To ensure the effect of discharge of the filter and saving water, the optimal discharge time of the filter was set to 20～30s in theory. Based on the experiments and error analysis, the optimal discharge time expression of 120 mesh filters was deduced. The results showed that the values of theory and test agreed well.