This study was conducted to increase the output torque of the turbine rotors of ship air-start motors. The turbine-type output of the air start motor was analyzed based on the pneumatic pressure and partial admission nozzle characteristics. The most efficient maximum output torque was analyzed and designed by changing the number of turbine nozzles and increasing the number of rotations. Computational fluid dynamics analysis was conducted and test results were analyzed to obtain the appropriate number of rotations according to the partial admission nozzle.