According to the experimental observation of Au atomic aggregations on a molten glass surface, we established a computational model to simulate Improved Restricted Cluster-Cluster Aggregation (IRCCA) on nonlattice substrates with regularly and randomly distributed impurities. In the model, the random diffusion step and rigidity rotation around the mass center of cluster were considered. The aggregation process was simulated and the influence of the distribution of impurity on the properties of aggregations was systemically investigated. The results show that regularly distributed impurities play a more important role in restricting the aggregation of clusters than randomly distributed impurities, resulting in a higher number density of fractal aggregates with smaller radius of gyration and fractal dimension.