Fault-block oil and Gas Field is one of special complicated reservoirs. For its development, No matter at home or aboard, the instances are not too many, and most of them are terrestrial oil reservoir. For ocean fault-block oil reservoirs, there are no instances that can be consulted. This paper aims at some ocean fault block oil reservoir .Gray relation model and fuzzy cluster analysis are combined to set gray fuzzy cluster analysis .Through a case analysis ,gray fuzzy cluster method is used to clustering of reservoirs. with the experiences that has been obtained, so that the foundation are provided for the development of some ocean fault block oil reservoir.