Abstract: The characteristics and spatial-temporal variations of soil fertility in paddy fields in river-network plains of Zhejiang were analyzed based on the recently acquired investigation data of farmland productivity. The results showed that the pH value of paddy soils in the study region inherited the characteristics of neutral and slightly acidic soils in the river network plains. However, soil acidification was significant due to longterm application of chemical fertilizers, and proportion of the soil with pH <5.5 increased. The effect of the changes in multiple-crop index and fertilizer application on soil organic matter and nitrogen accumulation in the paddy soil with long-term plantation of rice was not significant, but unscientific land leveling and longterm planting of vegetables and other economic crops could lead to a significant decline in soil organic matter and nitrogen. Status of phosphorus and potassium in paddy soil of the river-network plains were significantly improved in the past 30 years. On average, available P and K increased by 168.02% and 12.52%, respectively, as compared with the second national soil survey. However, there was still a large proportion of the soil with the deficiency in phosphorus and potassium. Affected by soil texture, contents of organic matter, total N, and available K in the soil of the Ningbo-Shaoxing plain and Wenzhou-Taizhou plain were higher than that of the Hangzhou-Jiaxing-Huzhou plain. The acidification was also more obvious in the Ningbo-Shaoxing plain and Wenzhou-Taizhou plain. It was suggested that soil testing and formula fertilization should still be an important technology to maintain the balance of soil nutrients in this region.