Ministructure is one of the basic research subjects in reservoir descripti on of the Shengli Oil\|field. It is interesting whether we can use the same contour interval for different reservoirs and whether the smallest the intervals of ministructure are the best in the application. The author gives account this problem in this paper. The mapof mini\|structure is applied to predicate performance of reservoirs and dispositions of infill wells in production. Therefore , the resolution of ministructure in practical production mainly depends on economic limit well spacing and dip angles of strata. The author has deduced the formulae of calculating the contour interval of ministructure map in condition of different reservoirs and the effect proved in the actual production is good