Abstract: This paper introduced the design and implementation of front circuit in the ultrasonic imaging logging instrument. This circuit mainly included impulse transmitting circuit, the boost circuit, the isolation limiter circuit, the filter circuit, and the differential detector circuit. MCU was used to control transmit circuit to incentive ultrasound probe in order to solve the receiving electromagnetic interference. The high-frequency amplifier and the differential amplifier were adopted to detect and amplify the signal envelope, so as to achieve a good signal of weak ultrasonic echo signal. Experiments showed that the circuit structure was simple and pratical, and could obtain a more satisfactory envelope signal.