The ROIC has an important influence on the non-uniformity of the IRFPA device. The non-uniformity model of general system unit was established by using the Taylor series of the dynamic nonlinear system function, and the ROIC non-uniformity model was established according to common architecture of analog ROIC. The spatial distribution characteristic of circuit statur parameters was modeled by mixing Berlin noise and Gaussion noise. The non-uniformity was evaluated with the spatial components of standard three demensions noise model. The time to sptial convertion from array signals to serial outputs was simplified by equal size convertion matrix. The non-uniformity of noise, multi-channel buffers and resposing nonlinearity were analized. The non-uniformity of a 320×256 array ROIC was evaluated by simulation and improved by circuit optimization based on the proposed model. Simulaiton results show that it can be used to evaluate the non-uniformity and to assist with non-uniformity engineering optimization of ROIC at the system level.