Code phase discriminator is the important part of the delay-locked loop, so its performance affects the pseudo-code tracking precision of receiver directly. Aim at influence of the input signal’s finite word-length effect on the discriminator’s performance, a new method based on signal statistical character was proposed and the effect of input signal’s finiteword length of unified early minus late amplitude discriminator on output performance was analyzed. Analysis and simulation show that the influence of input signal’s finite word-length effect in the case of high SNR(Signal-to-Noise Ratio) is more obvious than in the case of low SNR. The loss of pseudo-code tracking precision caused by finite word length increases as the increasing of input signal’s SNR. The deviation of the code phase discriminator with up to 4 bits almost has not influence on the pseudo-code tracking accuracy. This conclusion can be used to guide the low power and miniaturization design of receiver.