Abstract: The nutrient surpluses in regional agricultural land may partly discharge to natural waters, which will cause the eutrophication of rivers and lakes. Based on the long-term agricultural data of Changxing County in the south of Taihu Lake, the estimation of nutrient surpluses from 1949 to 2002 has been made. The results show that the annual specific nitrogen and phosphorus surpluses in the agricultural land have obvious increasing trends. The linear increasing rates of the surpluses are 3.66 kg N/(ha穉) and 0.65 kg P/(ha穉) for nitrogen and phosphorus respectively (R²=0.56, 0.46). In the 1950s and 1960s last century, the N-surplus increased slowly, but after the middle of 1970s it increased fast .By the year of 1996, it reached the maximum value of 319.9 kg/(ha穉). Since that time, it decreased. Before the earlier 1960s the P was in deficit. During 1975-1980 the P-surplus increased slowly and then it decreased. Since the middle of 1980s the P-surplus rose very fast and increased twenty times from 2.4 kg/(ha穉) in 1985 to 48.2 kg/(ha穉) in 1991. During 1992-1998, the P-surplus kept in high values between 35-45 kg/(ha穉). Since 1999 it decreased rapidly.