Brushless DC motor drive circuit is an important part of rotary steering system. High temperature work condition bring higher request of the temperature rise control of motor drive circuit. This article designs a high temperature resistant motor drive circuit based on Silicon carbide (SiC) MOSFET and analyses the cause factors of temperature rise from a general design perspective and analyses the security working characteristics of SiC MOSFET in deeply combined with the motor designing and the setting system’s working situation. Experimental results show that this circuit has characteristics of high temperature resistance, low temperature rise, high reliability and has used in rotary steering system successfully. In particular it provides technical references and depends in high temperature motor drive circuit designing.