The amplitudes and the phases of first to sixth harmonics of P-VEP waveforms were calculated, thus 12 parameters of the P-VEP waveform were obtained for the discriminatory analysis. The P-VEP waveforms of thirty-two normal eyes, thirty-one amblyopic eyes and thirty eyes with retrobulbar neuritis (RBN) were used to establish the discriminatory system. In the test of the discriminatory system, thirty of the thirty-two normal P-VEP waveforms were classified into normal group, thirty-four of the thirty-five amblyopic P-VEP waveforms were classified into amblyopic group, and twenty-eight of thirty RBN P-VEP waveforms were classified into RBN group.