A simulation model for diffusion and aggregation of atomic clusters with repulsi ve interactions on nonlattice substrates is established, and the aggregation pro cess of the silver atoms on charged silicone oil surfaces has been studied. It w as found that after the stable atomic clusters form, due to the repulsive intera ction among the clusters, the number density of the atomic clusters decays with time exponentially and the time constant is Oaa; statistically, the relative speed V between two clusters increases linearly with their distance L according to V=HL, where the constant H≈Oaa after deposition and then approaches zero with time. With the increase of the viscosity coefficient o f liquid substrates, the friction force increases and H decreases. A linear relation between the friction force and H is found with the slope k≈0 10±001 We show that the critical radius r11 of the clusters, abo ve which the atomic clusters start to carry charges, is related nearly to the at omic affinity, i.e., the energy needed for the cluster to carry an extra electro n. It is found that H and Oaa increase slowly with r11 and their slopes are 12±03s-1-1μm-1-1 and 16±06s-1-1μm-1-1, respectively. Our simulation results are in agreement w ith the previous experimental findings.