Abstract: Acoustic signal generated in the laser deep penetration welding process is an important parameter for quality detection. In this paper, welding experiments were performed on a 3.5 mm thick carbon steel plate with welding speed of 3 cm/s, 4 cm/s and 5 cm/s respectively. Three typical keyhole shapes of were obtained, namely flat shape, conical shape and spoon shape. The resonant frequencies of the acoustic signal of three typical keyholes obtained in the experiments are 1503.9Hz, 1894.53Hz and 2792.96Hz by time-varying frequency analysis s. The predicted oscillation frequencies of the keyholes by simulation are 1453.125 Hz, 1890.625 Hz and 2 750 Hz, which agree the experimental results within 5% errorss. The results show that the proposed model for predicting the acoustic radiation generated by the keyhole vibration in laser deep penetration is effective.