The non line of sight imaging technique is for the indirect observation of objects that cannot be observed directly.In this paper,the laser light is used to illuminate the intermediate medium,the light is reflected multiple times through the intermediate medium,and the echo signals are received by the APD(Avalanche Photon Dide) array.Then,the time delay estimation is performed using the quadratic correlation method to calculate the return time of the echo signals,and localization of non line of sight hidden objects is finally accomplished.The experimental results show that the proposed method can quickly get the location of objects in non line of sight,and it is more accurate than using cross correlation in low signal to noise ratio environment.