The invention discloses a harmonic wave measurement circuit which comprises a digital signal processor circuit; a micro mutual inductor array circuit; an analog-digital converter circuit communicated and connected respectively with the digital signal processor circuit and the micro mutual inductor array circuit, the micro mutual inductor array circuit isolating and converting the voltage and current of a power grid into secondary voltage analog signals which are sent to the analog-digital converter circuit where they are converted into secondary voltage digital signals and then sent to the digital signal processor circuit for rapid fundamental and harmonic calculation; a real time clock circuit connected with the digital signal processor circuit; a liquid crystal display communicated and connected with the digital signal processor circuit; and a button array connected with the digital signal processor circuit to set of the mutual inductor and to adjust the real time clock. According to the invention, an operational amplifier is not used, but rather a single positive power supply is used. Due to the reduced number of components, the circuit has a smaller size, consumes less power, becomes cost effective to manufacture and provide reliable performance.