Membrane crystallization, as a new separation process, was developed in the past few years. The new crystallization technique claims to be capable of producing perfect crystals under suitable operating conditions. In this study, membrane crystallization on lysozyme was discussed in this work. The influence of various membrane crystallization conditions on the crystal habit and quality of lysozyme was studied, and these conditions include protein concentration, precipitant concentration, the flow velocity of crystallization solutions, the flow velocity and concentration of stripping solutions, the pH and also ion strength of crystallization solutions. The changes of crystallization solutions concentration with time and the induction time were also studied. Furthermore, crystallization conditions were optimized, and the IR spectra from crystals obtained were made. Perfect lysozyme crystals were obtained. Two different crystal forms have been obtained, depending upon protein concentration, pH and precipitating salt employed. Compared with the traditional crystallization methods, membrane crystallization is more rapid and with slower initial protein concentration. In addition, membrane crystallization can control the crystallization process better, and better crystals were obtained.