On the basis of a study of the internal，interlayer and plane heterogeneity of the reser— voirs of the lower submember of the Sha一3 member in the Machang Oil Field，this paper analyses their control factors，proposes the synthetical evaluation method of heterogene— ity，and evaluates reservoir heterogeneity．Reservoir heterogeneity is controlled by its sed- imentary environment，epigenesis and tectonic movement．Internal heterogeneity is very seiious and the interlayer,and plane heterogeneity is relatively serious：The heterogeneity of the sand group iS more serious than that of the substratum．The evaluation shows that moderately heterogeneous reservirs are widespread.