Abstract: Effects of irrigation water and N fertilizer types on soil microbes and enzymes are poorly understood. This study aimed to evaluate the effect of different irrigation water and N fertilizer types on soil microbial biomass and enzymatic activities. A 2-year experiment (2015-2017) was conducted at the Tongzhou Experimental Station of Tongzhou District, Beijing, China(39°42′6.93″N, 116°41′2.31″E). The experiments utilized a factorial randomized complete block design with 8 treatments (2×4) in 3 replicates. The first factor had 2 irrigation water types (fresh water (FW) and reclaimed water (RW)), and the 2nd factor had 4 N fertilizer types (no nitrogen, urea, ammonium sulfate, and slow-release urea). Physicochemical, microbe and enzyme analyses from soil and water samples were determined. The results showed the contents of SOC, SON, DOC, DON, TN, NO3--N, and NH4+-N in different treatment soils were significantly different across crop seasons(P<0.05). The average contents of DON in soils irrigated with RW are significantly higher than that in soils irrigated with FW (P<0.05). Fertilization increased the SOC, SON, DON, TN, and NO3--N contents in the soils significantly (P<0.05). No significant interaction between irrigation and fertilization on the soil SOC, SON, DOC, DON, TN, NO3--N, and NH4+-N contents. the DON content in the soils irrigated with RW was average 8.33% significantly higher than in the soils irrigated with FW (P<0.05). The SOC, SON, DON, TN and NO3--N contents in the soils fertilized with inorganic N was on average 8.35%, 10.13%, 11.75%, 11.60% and 92.99% significantly higher, respectively, than that in the soils fertilized with no nitrogen (P<0.05). Soil bacterial biomass under different treatments ranged from 9.59 to 12.18 nmol/g. The soil actinobacterial biomass values under different treatments ranged from 1.01 to 1.24 nmol/g. The soil G+ bacterial biomass values under different treatments were 6.10- 6.73 nmol/g. Compared with FW and RW irrigation significantly increased the soil bacterial, actinobacterial, and gram-positive (G+) bacterial biomasses and total phospholipid fatty acids (PLFAs) by 7.60%, 10.48%, 4.97% and 4.88%, respectively. N fertilization significantly increased soil bacterial biomass by 13.42%-17.34% and increased the total PLFAs by 8.12%-11.19%. Compared with FW, RW irrigation did not significantly increase soil urease, catalase and invertase activities. N fertilization did not significantly increase soil urease, catalase and invertase activities. Soil microbes and enzymes were more active in the soils fertilized with slow-release urea. These results indicate that actinobacteria and G+ bacteria grew more quickly and could more efficiently utilize the DON introduced by the RW and that the soil bacteria could more efficiently utilize NO3--N introduced by the fertilizers than the other microbes. RW irrigation and slow-release urea fertilization were more effective to increase the soil microbes and enzymes. For better soil quality, higher yields and save water resources, drip irrigation with RW under slow-release urea fertilization was recommended for summer maize-winter wheat crop rotation.