A clean production technique, which can reduce wastewater pollution for gelatin plant in pH, suspended COD and Ca 2+ , has been proposed. Precipitated the lime from lime wastewater produced by lime process, then this alkali water without lime is added to another acidic wastewater produced by pickling process to e CaHPO 4. But in traditional technique, the lime wastewater with lime is added to pickling wastewater directly, little lime wastewater was consumed and large amount of lime wastewater, which contains high pH, high-suspended COD and high Ca, and is difficult to treat by biological treatment, is produced for gelatin plant. It is proved by the experiment that the final wastewater produced by the clean production technique has lower pH for the pickling wastewater consuming large amount of lime wastewater. It has lower COD for all the suspended COD and partial soluble COD being separated from the wastewater absorbed by CaHPO4 sedimentation, and that it has lower Ca for it is no longer the saturated lime solution.