The invention provides a current sensor with temperature stability and its measuring method. The current sensor comprises a sensor detection probe, an excitation circuit module, and a detection circuit module. The sensor detection probe comprises an annular magnetic core, an excitation winding and a secondary winding. The excitation winding and the secondary winding are wound around the annular magnetic core. The excitation circuit module comprises a voltage follower, a dual limit voltage comparator, a MOSFET driver chip and a half bridge excitation circuit. The half bridge excitation circuit comprises an upper MOSFET device and a lower MOSFET device, two capacitors and a direct current power supply. The specific connection relation is: the high input end and the low input end of the MOSFET driver chip are connected with the output end of the dual limit voltage comparator; and the high output end and the low output end of the MOSFET driver chip are connected with the driving ends of the upper MOSFET device and the lower MOSFET device of the half bridge excitation circuit. The input end of the dual limit voltage comparator is connected with the output end of the voltage follower. The middle end of the two capacitors of the half bridge excitation circuit is connected with one end of the excitation winding.