Abstract: Single event transient (SET) induced by high energy single particle radiation is the main threat to space application electronic system reliability. The evaluation and measurement of SET is the key to improve the performance of radiation hardened intergrated circuit. In view of the single event transient generated by the combined circuit, an improved circuit-level simulation method combining charge collection sensitive volume (SV) and bipolar diffusion mechanism for SET with heavy ion incidence was presented. The physics based multi-node charge collection model was built by analyzing layout characteristics such as active region geometry and heavy ion incidence angle. As the charge sharing effect and parasitic bipolar amplification effect considered, the established method which was integrated in the developed TREES software was used for evaluating SET in the 65 nm commercial cell library. The results show that the SET cross sections and pulse width distribution can be calculated and compared, which offer reference data for SET filter design.