Water-soluble carboxymethyl chitosan was prepared by chemical modification of N,O- carboxymethyl chitosan with chloroacetic acid and chitosan as raw materials. Carboxymethyl chitosan microspheres and carboxymethyl chitosan microspheres loaded with astaxanthin were prepared by emulsion method. The morphology, dispersion and particle size of carboxymethyl chitosan microspheres were investigated. The results show that the optimal preparation conditions of microspheres are as follows: The content of carboxymethyl chitosan (based on water phase mass, the same below) was 1.0%, the volume ratio of oil to water was 1∶1, the content of Span 80 (based on oil phase volume, the same below) was 4.0%, the content of glutaraldehyde (based on oil phase volume, the same below) was 7.5%, and the shear rate was 4000 r/min., IR test showed that the microspheres were successfully loaded with astaxanthin, and the loading rate and encapsulation rate were 10.74% and 67.24%, respectively, when the initial astaxanthin dosage was 20mg.The release rates of astaxanthin microspheres loaded in simulated gastric juice and simulated intestinal juice were 10% and 85%, respectively. Carboxymethyl chitosan can be used as a drug carrier.