[Objective] We investigated the variations of soil organic matter in paddy land of Hangzhou suburb over the last 30 years in order to provide basis for accurate soil fertility management and high intensive agricultural production.[Methods] Historic materials and current soil quality survey data were collected and compared to investigate the variations of soil organic matter.[Results] From 1982 to 2012, the mean content of soil organic matter decreased by 2.95%. The changes of soil organic matter varied with soil types. The mean content of soil organic matter in culture muddy-sandy field, silt paddy land, Fe-accumuli-stagnic anthrosols, muddy-sandy field and silt loamy paddy land showed an increasing trend, especially, in culture muddy-sand field, soil organic matter increased by 22.86%. In contrast, the mean content of organic matter in degleyed clayey paddy soil, blue silt loamy paddy soil and yellow loamy paddy soil showed a decreasing trend, and this decreasing trend in degleyed clayey paddy soil reached to 22.59%.[Conclusion] The content of organic matter in the paddy soils changed greatly during the past 30 years, and this change varied among different soil types. Fertilization structure, tillage practices and farming system were the main reasons that cause the variations of soil organic matter.