A two-stage pulse tube refrigerator equipped with three rotary valves has been constructed. One rotary valve controls the flow of the main gas flowing through the regenerators, and other two valves are used to modify the phase angle of the first and second stage through the room temperature side of the pulse tubes. The phase angles at the room temperature side of the first and second pulse tube relative to the main pressure oscillation can be changed independently. Besides the phase-angle dependence, the performance of the refrigerator was also investigated by changing the duration time connecting to the high- and low-pressure side of the main gas flow valve. When lead shots are used for the regenerative material at the second stage, the lowest temperature of 10.8 K was obtained. The experiments to optimize the working conditions are still on going and will be reported at the meeting.