A two-year field experiment under rice/wheat rotation system in Tai Lake region in Jiangsu Province of China was carried out to study the effect of digested pig slurry (DPS) on yields and nitrogen use efficiency of rice and wheat. The results showed that the treatments of pure chemical fertilizer (NPK) application and combined use of chemical fertilizer and DPS obtained significantly higher biomass and grain yields of rice and wheat than the no fertilizer control (CK). The treatment of N75% (75% N substituted) and N split application had the highest rice biomass and yield, which were 2.7% and 7.5% higher than the NPK treatment, respectively. The highest wheat biomass and yield, which were 15.9% and 7.8% higher than the NPK treatment, was found in the treatment of N50% (50% N substituted). The increased yields of rice and yield by combined use of DPS and inorganic fertilizer were mainly attributed to the increased numbers of panicle and filled grain. The highest N accumulations and N recovery efficiencies (NREs) of rice and wheat occurred in the treatments of N75% and N50% (50% N substituted), respectively. In the range of 50%-100% N substitution combined with N split application, both agronomic nitrogen use efficiency and partial factor of productivity of N fertilizer of rice and wheat were higher than the NPK treatment. N distribution proportion between different rice and wheat organs showed that combined use of DPS and inorganic fertilizer promoted N transfer into grains. Within the same substitution ratio, split application of DPS enhanced the grain yield, N accumulation and N use efficiency of rice and wheat than base application. The highest P contents in roots and leaves of rice and wheat appeared in the treatments of N75% and N100%, respectively. The best N substitution ratios of between 50% and 75% by DPS for rice and wheat could promote crop growth and N uptake and split fertilization was more suitable than base fertilization when DPS and chemical fertilizers were combined use in rice and wheat.