Abstract: Acrylic resin as coated material, N-(n-butyl) thiophosphric triamide(NBPT) and dicyandiamde(DCD) as biological inhibitors, with Fluid Bed spraying biological inhibitors on urea granular surface and coated it with acrylic resin afterward, four coated urea fertilizers were made for monitoring slow/controlled effects of coated fertilizers in distilled water. The results show that the film is integrated on urea core surface, coated material is uniformity distributing with coating and combining with urea core close, and the surface is smooth. NBPT and DCD combined with urea core closely, coating layer covered closely the inhibitors surface in the coated fertilizers made by such a technology. The film was able to control urea release availably. The release date was between 19 d and 30 d in distilled water. The preliminary solubility was lower than 15%, and differential solubility was between 0.25% and 2.5% approximately. The correlation of accumulative urea nitrogen released from coated fertilizers in distilled water with time was found to conform to a quadric equation in one variable, with "S" pattern curve for the urea nitrogen accumulative release rate of the coated urea.