Aiming at the real-time detection and weak echo signal characteristics of push-broom airborne laser detection and ranging (LADAR) system, one algorithm for echo time abstracting is researched based on Gauss normal echo signal. The algorithm is fast, precise and easy to design in hardware, which achieves high precision distance detection as a result. The existing problems and accuracy of the traditional waveform centroid algorithm are analyzed. In order to reduce the influence of the data precision and noise interference on the hardware, a corrected approach based on the median method is proposed, which can effectively weaken the layered phenomenon in hardware implementation of algorithm. A mathematical model is established by MATLAB and the simulation experiment is carried out. The simulation results show that the corrected centroid algorithm has better robustness compared with the traditional centroid algorithm and Gaussian fitting algorithm. The accuracy can reach 0.5 ns, which is 45% higher than that of the traditional centroid when the SNR is 5 dB. The proposed algorithm can achieve higher accuracy than Gaussian's with the SNR becoming greater, which reaches 0.01 ns theoretically. The corrected algorithm is simple and efficient. In addition, real-time judgments and correction on the results of the centroid are made without increasing the complexity of the system. Owing to the simplicity of the algorithm, it is suitable for transplanting to FPGA platform. The algorithm has been utilized for push-broom airborne LADAR system information processing circuit. The results of experiment verify the validity of the theoretical analyses and show that the algorithm can achieve the ranging accuracy of ±7.5 cm, which meets the real-time requirements in practical application.