In order to guarantee stable and reliable operation of micro axial- flow blood pumps,the temperature riseof electromagnet in the large- gap magnetic drive system should be investigated and accurately controlled.In thispaper,the temperature distribution,heat loss,heat flux and thermal gradient of various components of the systemwere analyzed,and a simulation model of the thermal field of the electromagnet was established.Then,the distri-bution and variation law of the system temperature field were obtained via finite element simulation and experimentinvestigation.Finally,to meet the requirements of human body adaptability and long- term running of the electro-magnet,the electromagnetic and environmental parameters of the electromagnetic drive system were simulated andoptimized by taking a suitable temperature rise of the electromagnet as the target.The results show that the tempera-ture rise of the electromagnet can be effectively reduced by decreasing the loss and improving the heat emission con-dition of the electromagnet; and that the highest temperature of the electromagnet does not exceed 50 ℃ when thecurrent of electromagnet coils is lower than 0.56A and when the air velocity is higher than 3.5m/s.