Abstract: AGPBSim (Animal Gene-Pyramiding Breeding Simulation) is an individual-based, genetical information integrated simulation program. It was developed to investigate gene-pyramiding breeding given base population sizes, initial allele frequencies and selection strategies. The process of gene-pyramiding breeding was measured using population hamming distance, superior genotype frequency and average phenotypic values. AGPBSim is high flexible at various levels: four cross schemes and three selection strategies and trait architecture using various genotype-phenotype models were integrated in gene pyramiding breeding simulation. The GUI design of AGPBSim can facilitate design of gene-pyramiding breeding strategies by performing virtual breeding simulation on this platform.