In order to compensate the shortness of the pseudorandom ranging system performance research, pseudorandom generator of 1 GHz and 2.5 GHz is realized by field-programmable gate array. Using 50 m as tested range, two channel photons arriving times are measured and calculated by fast Fourier transformation to obtain cross-correlation wave. Based on that, the cross-correlation mathematic model is set up and the parameter evaluation method is used, Markov technique is utilized to optimize parameter iteration. Finally, the cross-correlation wave is reconstructed and the range evaluation value is obtained. The ratio of pseudorandom pattern of 1 is 1% and the detected photon counting rate is 2×106 s-1. The research result manifests that in low background condition, with the increased integration time, the signal to noise ratio increases, which agrees with the theory result. In high background condition, with the increased integration time, the deviation amplifying speed with direct peak value is greater than the speed with the proposed method. Compared to the peak value method, the whole resolution is improved. With the integration time of 0.001 s, the resolution is increased from 7.3 cm to 4.62 cm. In addition, the resolution of 1 GHz is much lower than the resolution of 2.5 GHz. At the same bit speed, the effect of background noise on resolution is weakened.