Abstract: Potted plant method and "water-marinating method" were used to measure Osmocote which is polymer-coated fertilizer from Scotts Co. of U.S.. The results showed that the N of fertilizer release property was in accordance with linear relationship, the nutrient release time of fertilizer in "potted plant method" was 118.1 d that matched the mark of fertilizer; the nutrient release periods in international common use method and "water-marinating method" were 86.4 d and 54.7 d with some errors. "Intensified marinating method" was put forward in paper that fertilizer was marinated in 80℃, 1∶20 ratio 2% hydrochloric acid solution and mixed round the upper solution at the same time. The paper established the relative equation between the results of "potted plant method" and "intensified water-marinating method" and presented the method which was used for online measuring and predicting fertilizer release property in industrial production, which afforded valuable references for compiling fertilizer introduction. The verified results showed that the average absolute error was 5.25% and the average relative error was 1.71% compared with "potted plant method".