The content of EPS affects the characteristics of sludge and formation of the granular sludge.To study the effect of substrate concentration and type on the EPS content and the sludge settling performance, six SBR reactors with different ammonia concentrations and different substrates were used. The results showed that the EPS content increased with the increase of ammonia concentration only when ammonia nitrogen concentration was 60-200 mg／L, but did not increase significantly when the ammonia nitrogen concentration exceeded 200 mg／L. The relationship between the ratio of polysaccharide to protein and ammonia concentration was a linear correlation, with R² of 0.972 3. The EPS was influenced by the substrate type, higher content of polysaccharide with glucose as organic, and higher content of protein with domestic waste water as substrate. The protein and polysaccharide were biodegradable, which could be used by microorganisms as carbon source and energy when the substrate was deficient. The sludge sedimentation could be affected by the EPS content, and the SVI decreased with the increase of EPS content.