Abstract: To improve the detection performance of marine radar, the application of multifractional Brownian motion to modeling the radar sea clutter in the scanning mode is studied. It is verified that real sea clutter data submit to a non-Gaussian distribution with asymmetry, high peak and heavy tail, and have fractal characteristics. In some cases the assumption of multifractional Brownian motion for the real data is satisfied. On the basis of this analysis, the real data are modeled by using the multifractional Brownian motion, and the time-dependent Hlder function of the real data is calculated. The results show that the Hlder exponents of different regions are not the same, and the Hlder exponent of target is significantly larger than that of the sea clutter. The research results are helpful to design a reliable detection method.