Considering the influences of a magnetic field B,the concentration of the electrolytic solution and the probability of reaction P_s,a series of interesting patterns that are in good agreement with experiments', are observed.It is found that the pattern of clusters and their fractal dimensions depend strongly on the magnetic field which is presented by a rotation velocity of the diffusing particles ω in the model.Our simulation shows that the growing cluster transits from fractal to non-fractal with an increasing of magnetic field intensity.A relative high magnetic field and a greater n or f result in a non-fractal cluster.With an increasing intensity of magnetic field,the decreasing of P_s accelerates the growing cluster from fractal to non-fractal pattern.