Using the dry sieving method, a study was conducted to investigate effects of long-term (23 years) fertilization on contents and characteristics of soil aggregates in red paddy soil. The long-term fertilization experiment had 6 treatments, i.e. ①CK (without any fertiliazation), ② N (only N fertilizer), ③NP (combination of N and P fertilizer), ④NPK (combination of chemical fertilizer), ⑤NPKM (combination of chemical fertilizer with manure), and ⑥OM (manure). Results showed that content of aggregates of red paddy soil was mainly affected by organic manure. Compared to CK, Treatment NPKM and Treatment OM was 25.4 % and 24.6 % higher respectively in content of soil aggregates 3~5 mm in size, but 70.6%~71.1% and 113.6%~121.7% lower respectively in content of aggregates 0.05~0.25 mm and <0.05 mm in size. However, there was no obvious difference between Treatment NPK and CK. In addition, the values of MWD (mean weight diameter), GMD (geometric mean diameter) and D (fractal dimension) of soil aggregates in Treatments NPKM and OM all increased dramatically, and it was also found there were significant correlations between the three indexes and crop yield, suggesting that MWD, GMD and D could well cited as indicators of soil fertility. Besides, significant correlations between contents of aggregates 3~5 mm, 0.05~0.25 mm and <0.05 mm in size and crop yields were also observed. It could thus be concluded that these three fractios of aggregates could be used as a good physical indicator to evaluate fertility of red paddy soil.