Fe-Co rich particles in the Alnicos samples thermomagnetically treated fo for various times at 800℃ have been found to be of self-similarity and of fractal characteristics both in two- and three-dimension space. Fe-Co rich particles for 1. 5, 3 and 5min treatments have shown a different fractal nature both in two- and in three-dimension space compared with the case for 10min, which implies that Fe-Co rich particles evolved through fifferent rent kinetic mechanisms. The fractal dimensions for 1.5, 3, 5min as well as 10min treatments derived from the SAXS data in three-dimension space are in good agreement with the theoretical dimensions for two models introduced, respectively. The fractal dimensions in two-dimension space greater than the theoretical ones for two models can be attributed to strong anisotropy of Fe-Co rich particle evolution in three-dimension space. Fe-Co rich particles in the Alnicos samples thermomagnetically treated fo for various times at 800 ° C have been found to be of self-similarity and of fractal characteristics both in two- and three-dimension space. Fe-Co rich particles for 1.5 , 3 and 5min treatments have shown a different fractal nature both in two- and in three-dimension space compared with the case for 10min, which implies that Fe-Co rich particles evolved through fifferent rent kinetic mechanisms. The fractal dimensions for 1.5, 3 , 5min as well as 10min treatments derived from the SAXS data in three-dimension space are in good agreement with the theoretical dimensions for two models introduced, respectively. The fractal dimensions in two-dimension space greater than the theoretical ones for two models can be attributed to strong anisotropy of Fe-Co rich particle evolution in three-dimension space.