Abstract: Act glutaraldehyde as enhance modifier to prepare primitive Antarctic krill protein/sodium alginate (AKP/SA) primary fibers using wet spinning process, and the high strength Antarctic krill protein/algae (HAKP/SA) composite fibers were fabricated via online thermal crosslinking technology realizing thermal crosslinking reaction through primary fiber spinning line. Thermal crosslinking temperature was defined by Rotational viscometer. The effects of crosslinking degree on microstructure and moisture absorption performance of composite fiber were studied, and the variations of mechanical properties and crystallization properties of composite fiber after reinforcement were tested. The results show that glutaraldehyde can perform effective thermal crosslinking reaction when temperature is 80℃. AKP/SA composite fiber has good moisture absorption performance, moisture absorption rate of 7.3%, the moisture absorption performance of composite fiber decreases and moisture balance time shortens with the increase of crosslinking degree. HAKP/SA composite fiber still exists in amorphous form. Surface of composite fiber shows uniform groove microstructure. Mechanics performance test shows that the fiber breaking strength after reinforcement increases by 13%.