To explore the inhibitory effects of the biochar made by dairy manure as raw material against soil nitrogen fertilizer leaching, this paper characterizes and analyzes the structure and elements of dairy manure biochar, and carries out manual simulations of soil column experiments on soil leaching, based on which we study the impacts of dairy manure biochar on 1) the pH value of soil leachate, and 2) overall cumulative loss amount and concentration of NH4 +, NO3 -, and total nitrogen. The results show that compared to dairy manure, dairy manure biochar possesses more developed tubular hole structures, and has 200% and 10% more K and Ca substances, respectively. Concentration of NH4 + and NO3 - were gradually reduced with the addition of dairy manure biochar at 0%、1%、2%、 3%、4% and 5%, respectively. The leaching time of NO3 - on soil was delayed with the addition of biochar．When the addition of dairy manure biochar is 4～5%, the inhibitory effects of dairy manure biochar on soil nitrogen fertilizer leaching were most effective; compared to the addition 0% of dairy manure biochar, overall cumulative loss amount of NH4 +, NO3 -, and total nitrogen are reduced by about 16%, 32% and 32%, respectively.