Abstract: The core on-line monitoring system SOMPAS was developed by Shanghai Nuclear Engineering Research & Design Institute Co.,Ltd. (SNERDI). SOMPAS uses core nuclear design system SCAP newly developed by SNERDI as the neutronics calculation kernel. Before SCAP is applied in SOMPAS, it must be fully tested, especially compared with the measured values of the power plants to verify its accuracy, reliability and applicability. The objects of verification are 300 MWe nuclear power plants independently developed by China, including a total of 32 cycles of the measured values for Qinshan and Chashma unit 1 & 2. The numerical calculation results show that the neutronics calculation kernel SCAP has high calculation accuracy and reliability, and meets the requirement of neutronics calculation kernel application in the SOMPAS.