Abstract: In order to reveal the variation laws of radiation effect and internal charge collection in static random access memory (SRAM) so as to provide effective simulation data support for the device radiation hardening, a simulation method was proposed for determining three-dimensional sensitive volume parameters according to the on-orbit single event upset (SEU) of SRAM unit. Firstly, by combining simulations of device-level and circuit-level, the three-dimensional model was constructed using technology computer aided design (TCAD). The single event transient current was obtained by simulating heavy ion incidence from different directions, and then the current was input into the circuit-level model of the 65 nm SRAM unit as a fault to simulate SEU. Finally, the SEE-induced three-dimensional sensitive volume parameters of the 65 nm SRAM unit were obtained.