To control environmental pollution, the Wastewater Treatment Plant (WWTP) plays a vital role in treating wastewater to comply with quality standards before being discharged into the environment. However, not all WWTPs have worked optimally, so the periodic evaluations must be carried out to determine problems and what efforts can be made to improve WWTP processing quality. This study aims to evaluate the Jababeka 1 WWTP, which functions to treat wastewater in Industrial Area 1 and Industrial Area 7, which are in the Jababeka Industrial Estate (KIJ). Evaluation is carried out by comparing the actual processing efficiency with the related literature. Evaluation is also carried out by simulating the process and operation of WWTP using STOAT software. STOAT is one of the WWTP system modeling software mostly used to predict the wastewater treatment plant’s performance. The test results show that for the efficiency of Jababeka 1, WWTP removal for parameters BOD, COD, and TSS are 90%, 93.02%, and 96.12%. Based on the data obtained, modeling based on sensitivity analysis was also carried out using STOAT software to determine the most significant WWTP performance parameters. It was found that the wastewater discharge was the most critical parameter affecting the removal efficiency of TSS and BOD.