The scheme optimized selection method of automobile automatic transmission is presented by analyzing the planetary gear mechanical construction of hydraulic automatic transmission and adding the necessary constraints of the design objective. The method is using the lever analogy to find out all the combinations of2 degree of freedom,2 rows planetary gear train. After the exhaustion,according to the nomograph of the planetary gear train,the feasible combinations would be composed into its clutching sequence. From a set of desired speed ratios the basic ratio of each row can be got. Using the basic ratios as the criterion,the number of feasible combinations will be decreased dramatically. By using this method,the numbers of the combination of the structural synthesis can be decreased and the clutching sequences synthesis efficiency will be increased effectively.By using this method,the optimized selection of nine-speed parallel-connected planetary gear mechanisms automatic transmission is realized and four feasible schemes are obtained.