In order to avoid damage to the inner surface of the cavity-containing parts and improve processing efficiency, it is necessary to determine the number of pulses required to penetrate the material during the laser drilling process. The photodiode is used to detect the light signal on the upper surface of the material during the laser percussion drilling processof GH3536 superalloy. And the acquired voltage signal is used to judge whether the material has been penetrated, then the number of pulses that have been applied when the material is penetratedcan be recognized. The results denote that the change of the voltage signal amplitude generated by the selected photodiode can reflect the change of the laser reflected light intensity on the upper surface of the material caused by the change of the hole morphology during the drilling process, thereby the drilling process can be divided into 3 stages, and it is successfully identified that the number of penetration pulses under the test parameters is 14.