Abstract: Thermal-hydraulics of process systems is a fundamental discipline closely associated with operational safety and efficient operation in the nuclear energy sector, and corresponding simulation tools have become an indispensable support for nuclear power engineering. Nevertheless, domestic self-developed simulation products currently suffer from insufficient maturity and limited practical engineering applications. To address this issue, this paper conducts research based on SimFluid, an independently developed thermal-fluid system simulation and analysis software, targeting the operational performance analysis requirements of nuclear boric acid proportioning systems. Relying on the built-in mechanism model library and performance database of the software, forward modeling without calibration is completed according to the system design documents. Taking the commercial software FloMASTER as the reference benchmark, steady-state and transient accuracy verifications under multiple operating conditions are carried out. The results demonstrate that the relative error of key simulation parameters of SimFluid is less than 0.05%, its dynamic characteristics under all working conditions are highly consistent with those of the benchmark software, and it can accurately reproduce the proportioning law of the system. This study verifies the engineering accuracy of forward simulation using SimFluid and provides self-developed software support for nuclear power engineering.