Results of simulation, pot and field experiments with brown earth showed that (1) the inhibition rate of soil urease activity by hydroquinone increased with increasing application rate of the latter, and the duration necessary for the restdration of urease activity decreased with decreasing application rate of this organic compound; (2) applying proper amount of hydro-quinone increased the utilization rate of urea-N by springwheat and decreased the gaseous loss of urea-N; (3) applying proper amount of hydroquinone, and urea before sowing without ropdressing of urea in growing period markedly increased the yield of maize; and (4) in treatments of applying hydroquinone, no accumulation of this compound was found in soils, stems and grains.