Self-pumped phase eonjugation(SPPC) hag been observed in KNSBN:Co crystals with sizes different. The dependence of phase conjugate reflectivity has been proved not only on the incident angle and incident position, but also on the laser wavelengths by experiments. Their experimental plots are shown respectively. The large crystal produce up to 73.0% phase conjugate reflectivity at 514.5 nm. The dependence of phase conjugate formation time on input intensity is shown. During producing the phase conjugation, the character of both intensities of the transmitted beam and reflected beam of the crystal varying with the time is presented. The reason for producing threshold intensity is explained.