Abstract: Objective : Isolation and purification of L- citrulline in seeding watermelon by resin column chromatography were studied. Method:The behavior of static adsorption,desorption and dynamic balance experiments of three kinds of cation exchange resin column was compared. The 001×7,D001 and D061 resins were employed to separate and purify the L-citrulline extracts from seeding watermelon. By investigating the temperature,p H,concentration,adsorption breakthrough curve,concentration of eluent and flow rate,further study on 001×7 column chromatography separation and purification of L-citrulline condition was discussed. By determination decolorization rate and adsorption rate of three different polar macroporous adsorption resins and activated carbon,the decolorization technology of extracts from seed watermelon was optimized. Results:It's the best to use 001 ×7 resin to adsorb and purify L-citrulline from seeding watermelon. The optimal purification conditions were as follows:temperature of 40⁵0 ℃,p H 3,velocity of 0.5 mol/L ammonia taken as eluent 0.5 m L/min,and volume of ammonia water 6 BV(bed volume). Decolorization technology using HZ-801 macroporous adsorption resin was better and the purity of L-citrulline could reach up to 96.6% after further recrystallization. Conclusion :The combination of 001 ×7 resin column chromatography and HZ-801 macroporous resin for separation and purification of seed watermelon L-citrulline was an effective method. The research had the significance meaning for fully using of seed watermelon resources and reducing high cost of L-citrulline in our country current situation.