The invention discloses a quenching method for a thin-wall type gear with an inner spline. Rapid quenching oil is adopted for quenching, the maximum cooling capacity of oil is 103 DEG C/s, and the oiltemperature is 65 DEG C; before component quenching, a stirring cycle is started, and the stirring speed is adjusted to be 1,300 r/min; during quenching stirring, a computer programming controlled 0-2,400 r/min stepless speed change stirrer is adopted for conducting segmented speed changing stirring on quenching oil, and pre-cooling stirring, high-speed stirring, decelerated stirring and slow stirring are included. The rapid quenching oil is adopted for quenching, and the conventional thought that isothermal step quenching oil is adopted for slow quenching for reducing and controlling deformation is broken; and through the proper segmented speed changing stirring speed and time, a new thought is provided for quenching deformation control.