Abstract: A method to extract model parameters based on PSO(Particle Swarm Optimization) algorithm is presented for BSIM SOI(Silicon on Insulator) devices in this paper.Using global optimization,this method has simple calculation and has low dependence on initial value.The use of float-encoding in this method avoids the error of digital transfer.Compared with parameter extraction method based on Genetic Algorithm,this method does not require crossover and mutation operations.And it can be easily understood and implement,and has high speed as well.Computation is very simple using this method and it does not require an in-depth understanding of the model equation or a lot of experience with parameter extraction.Using parameters found by this method,the simulation results are matched well with the measurement data.This method also can be applied to other kind of MOSFETs(Metal-Oxide-Semiconductor Field Effect Transistor) for global parameter extraction.