In the present study, four treatments with triplicates were designed with colored or un-colored rainbow trouts with average initial weight of (101.9±1.3)g. Un-colored rainbow trout was fed with diet containing 100mg/kg astaxanthin to study the deposition of astaxanthin in body (astaxanthin deposition group). Colored rainbow trout was fed with basal diet with 100mg/kg astaxanthin addition (positive control) or without astaxanthin addition (feeding degradation group), or deprived of diet during the whole feeding period (starving degradation group) to study the degradation of astaxanthin in body. The feeding trial last for four weeks. Samples, including muscle, liver and serum, were collected once a week, and measured with astaxanthin contents of flesh, liver and whole fish, serum carotenoids, flesh chromatism(L*, a*, b*), and flesh Salmo Fan score. Results showed that in astaxanthin deposition group, astaxanthin contents of flesh and liver, flesh a* value, Salmo Fan score of rainbow trout increased with feeding time prolonging (P<0.05), and kept stable in the 3rd week. There were no significant difference in these indexes between 3rd week and 4th week(P＞0.05). In the whole feeding period, astaxanthin content of whole fish tended rise, but axtaxanthin retention rate of whole fish tended to decrease. In the first week and in the fourth week, astaxanthin content and axtaxanthin retention rate of whole fish were 3.71 mg/kg, 8.59 mg/kg and 21.31% 15.26%, respectively. In both starving and feeding degradation groups, astaxanthin content of tissue, flesh a* and Salmo Fan score of rainbow trouts decreased with feeding time prolonging(P<0.05), but the decreasing trend of these indexes slowed down in the 3rd week. The decreasing speed of these indexes in starving degradation group was faster than those in feeding degradation group.. Results above showed that an addition of 100mg/kg astaxanthin in diet could make the flesh of rainbow trout present ideal red colour after three weeks feeding, but astaxanthin retention rate decreased with feeding time prolonging. For rainbow trout fed diet without astaxanthin or deprived of diet, flesh astaxanthin and a* value significantly decreased during feeding period, and starving make astaxanthin reduce more quickly than feeding diet without axtaxanthin. The degradation speed of astaxanthin in body of rainbow trout tended to slow down with time prolonging.