【Objective】Pig is one of the most farmed breeds in China. In 2020, there were 406.50 million pigs in China and 41.13 million tons of pork were produced. Meanwhile, hundreds of thousands of tons of pig slurry and manure were produced during pig breeding in China. Many nutrient elements needed for crop growth are available in pig slurry, such as nitrogen, phosphorus, amino acids, trace elements, etc. Returning pig slurry to the field is one of the best ways for its utilization. To solve the problem of pig slurry application on farmland, studies are required to determine the optimal amount of pig slurry needed for the application and reduce the possible environmental risks which are associated with pig slurry application. 【Method】The experiments were carried out in a self-made soil column with a volume of 42.41 L and were designed with 7 treatments, including no fertilization (CK), 50% (50%W), 100% (100%W), 200% (200%W)and 300% (300%W) replacement of chemical nitrogen fertilizer by pig slurry, 50% replacement of chemical nitrogen fertilizer by pig slurry + 50% chemical nitrogen fertilizer (50%W+50%C), and 100% chemical nitrogen fertilizer (100%C). The average number of spikes, chlorophyll content, spike and straw yield, nitrogen and phosphorus content in spikes and straw, and the changes in physico-chemical properties of soil leachate and the contents of nitrogen, phosphorus and heavy metals were analyzed. 【Result】The results showed that both 50% and 100% replacement of chemical nitrogen fertilizer by pig slurry could promote the growth of rice and wheat to varying degrees and increase the yield. However, the difference between treatments was not significant. The excessive application of pig slurry caused rotten roots and dead seedlings in rice, wild growth in wheat, and increased nitrogen and phosphorus concentration in soil leachate, which increased the risk of contaminating groundwater, and some indexes even exceeded the standard of Class IV water in the National Groundwater Quality Standard (GB/T 14848-2017). Also, the massive application of pig slurry caused the accumulation of Cu, Cd and Pb in the soil whereas Zn content did not increase significantly. The above results indicate that, the replacement of chemical fertilizer by pig slurry is feasible under appropriate conditions as shown in this experiment. 【Conclusion】It is suggested that the application amount of pig slurry should not be more than 200% replacement of chemical nitrogen fertilizer which have a better effect in promoting the growth of rice and wheat, fertilizing the soil and controlling environmental pollution risk of farmland.