When faults or disturbance occurs in AC/DC hybrid complex power grid, there have happened many generator, transformer and transmission line differential protection maloperation accidents caused by current transformer (CT) saturation, which seriously threaten the safe and stable operation of grid. As the analytical analysis of CT transient characteristics is very complex, it is urgent to develop the CT model which can accurately simulate the transient characteristics of CT in practical use. In this paper, different class (P, PR and TPY) protection CTs in practical use are taken to do physical test. Based on the test results and genetic and simulated annealing algorithms (GASA), the Lucas model parameters of practical CT are identified, and the simulation model is built in PSCAD which can simulate the transient characteristics of different class CT in practical use. The dynamic test verifies the accuracy and validity of the model in different typical power system transient conditions.