Abstract: The authors proposed a genetic model of crack system of the Permian carbonate reservoirs of the Sichuan basin. The model shows that structural fractures were developed inthe dense carbonate rocks due to tectonic activity, then the fractures were dissolved and enlarged,and various secondary pores,cavities and cracks were formed and connected with each other, generating a crack system with the function of reservoir and permeability for fluid flow. The crack system can continuously be reformed and may be filled during the long tectonic activity and diagenesis. The present valid crack systems are the final result of multicycle tectonic movements and diagenesis. Their distribution is regular and anisotropicor probabilistic.