Abstract: The experiment was conducted on the way of cultivated soil column, which was to study efficiency of fertilizing biogas slurry on nitrate accumulation and N utilization of Pennisetum according to fertilizing different levels N of biogas slurry(seven levels of N that was from N0 to N6 designed were 0, 5, 10, 20, 40, 80, 160 kg/ha of equivalent nitrogen fertilized,9 times for every 45 days of cutting period).The result showed that N levels of biogas slurry had an effect on the content of Pennisetum nitrate,and the relations between them were positive correlation. In high levels of N fertilizer,however,the contents of Pennisetum nitrate in different cutting periods were all less than 0.25% of toxic limits for nitrate.In addition,content of Pennisetum crude protein and production of CP were going up with the increased levels of N,the maximums were 21.35% and 44.09 g/pot, respectively. Analyzing the efficiency of N utilization, protein,physiological N,agronomic nitrogen and nitrogen partial factor productivity showed that efficiency of N utilization would be lower,and the loss rate would also be larger with the increasing N levels in biogas slurry. N content of soil column leaching analyzed showed that the quantity of N leaching had the trend of going up with increasing N levels,treatment N5 and N6 in one year were 80.69, 312.3 mg respectively. In addition,soil total nitrogen content of group N5 and N6 below 40 cm soil layer were also significantly higher than other groups(P>0.05). It was concluded that in one cutting period,the quantity of Pennisetum grassland absorbing N in biogas slurry was lower 360 kg/hm² of pure nitrogen,which should be reasonable.