Abstract: Field experiments were carried out to clarify the effects of reducing nitrogen topdressing with reclaimed water irrigation on rootlayer soil nitrogen residual of greenhouse tomato. Rootlayer soil mineral nitrogen residual, total nitrogen residual, plant biomass, tomato yield, partial factor productivity from applied N and apparent N loss of all treatments were analyzed. The results indicated that soil mineral nitrogen consumption of greenhouse tomato was mainly concentrated in 0 to 30 cm rootlayer, and compared with the conventional topdressing application with reclaimed water irrigation treatment, the yield and partial factor productivities from the applied N of the reducing nitrogen topdressing treatments were significantly improved. After the postharvest of tomato, soil apparent N loss of the reducing topdressing was significantly less than that of the conventional topdressing. Tomato yield is therefore notably improved under reducing nitrogen topdressing with reclaimed water irrigation, maintaining soil fertility, and which is an effective nitrogen management strategy of alleviating soil environment.