Drying methods of sediment samples are commonly divided into natural air-drying, low-temperature drying and freeze drying, the processing efficiency and time-consuming of three treatment methods are very different. In this paper, sediments were sampled from Taihu Lake, and dried under natural air, low temperature or freeze, then analyzed using the same method for the determination of total nitrogen (TN), ammonium (NH4+-N) and nitrate nitrogen (NO3--N). Statistical analysis of the results showed significant differences between sample treatments relating to the mean TN, NE4+-N, NO3--N concentration. Referring to dry samples, the average content of samples using freeze-dried method and air-dried method, were 1.07, 1.33, 0.91 and 1.01, 1.23, 0.68 for TN, NH4+-N, NO3--N, respectively. NO3--N content of dry samples was the highest. The ANOVA showed that there was no significant difference about TN, NH4(+)(-)N and NO3--N among the three methods. However, there were significant differences. when two methods were compared. The result of LSD showed that there were significant differences between Frozen-dried Method (B) and Dried Method (A) with p=0.039; and between Frozen dried Method (B) and Air-dried Method (C) with p=0.043 for TN. In addition, the correlation analysis results showed a significant correlation at the level of P < 0.01, suggesting that the effects of different pretreatment methods on TN, NH4+-LN and NO3--N extraction are holistic, not due to changes in individual samples. Compared with air-drying, low-temperature drying, freeze-drying process can truly indicate the nitrogen composition of sediments, it is an ideal way of sample drying.