Abstract: Grit chamber is an important equipment of pretreatment unit in wastewater treatment plant. In recent years, vortex-type grit chamber had been widely used in municipal wastewater treatment plant, however the inorganic particles yield was poor in practical operation. This article focused on the the poor operation effect and low inorganic particles yield in a vortex-type grit chamber from wastewater treatment plant. Specific measures including changing to a spiral curved blade, reducing the speed of the blade, and adjusting the distance between the blade and the bottom were proposed. After the modification, continuous testing was conducted on the vortex-type grit chamber of the plant, and it was found that the SS removal rate was significantly improved from 1.86% to 21.38%, with an average sand output of 51 kg/d. Meanwhile, the interception effect of COD was improved, which was conducive to reduce the carbon source addition into the subsequent biological tanks. Compared to the original chamber, the TN removal rate kept at a level of 0.9%, but TP removal rate was increased from 0.44% to 0.99%. In general, the vortex-type grit chamber was more stable and the inorganic particles yield was enhanced after the modification.