The model of radar sea clutter using fractal theory has a wide application in many research fields. This paper proposes inserting a time-varying random sequence in Fractional Brownian Motion ( FBM ) model for obtaining an approximate multi-fractal stochastic process to simulate the sea-clutter sequence based on the analysis of multi-fractal characteristic and FBM model. Through Matlab simulation and the comparison with the measured data，the result shows that the sequence produced by the model proposed in this paper is multi-fractal，which can effectively simulate the sea clutter.