An underwater pulsed-laser-sound-signal detection technique is introduced by combining the frequency-domain characteristics of the laser acoustic signal. The different attenuation characteristics of the laser acoustic signal at different frequencies are analyzed. To ameliorate the serious attenuation of high frequency components at long distances, a pre-compensation filter is added to the front end of the frequency-domain energy detector; the results of Monto-Carlo simulation show that the frequency domain energy detector with pre-compensation filter can effectively improve the detection performance of laser acoustic signal at a long distance.