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With the rapid growth of population, the rapid development of the global economy, a shortage of resources and environmental pollution has become increasingly prominent, especially fresh water resources and sewage discharge. Faced with the grim status quo, governments have taken the appropriate systems and measures to deal with this problem, then on the urgent need for high-precision instrument for the accurate measurement of liquid flow, ultrasonic flowmeter simple way to measure the high measurement accuracy, non-contact measurement, etc. came into being. From analysis of the ultrasonic flowmeter hotspot in recent years and abroad, The Ultrasonic Flowmeter research development direction of high-precision, high stability, intelligent, and low power consumption. Based on the principle of transit-time measurement, in-depth exploration and research of key technology of high-precision, low-power, the research points to the following aspects: 1, in-depth analysis of the state of motion of the fluid in the pipe, on this basis, deduced the turbulent and laminar flow state, the correction coefficient of the surface of the average flow velocity, so that the calculated flow rate is closer to the true value, to improve the measurement accuracy; resonant characteristics based on the ultrasonic transducer and ultrasonic wave propagation characteristics of the proposed ultrasonic transducer electric, acoustic matching, through the drive circuit so that the ultrasonic transducer electrical matching, at the resonance point in the ultrasound transducer internal plus damping mass, the crystal from the stationary state after the vibration can be quickly restored, through sound, electrical matching improve the stability of the ultrasonic signal, enhance accuracy. 2, combined with the ultrasonic flowmeter threshold comparison model and an ultrasonic signal over the advantages of zero from its voltage amplitude change impacts, the zero crossing threshold comparison model, the threshold comparison model can effectively remove the receiving transducer receives the ultrasonic signal before the interference signal, and the ultrasonic zero does not change with changes in their voltage amplitude changes, combined with the advantages of both can be effectively suppressed the great range of the static time difference changes, the experiment proved that the method can be well suppressed static zero drift; in 53H algorithm based on improved algorithm, then the actual measured value with this estimate, by the time difference of the actual measurement data of discrete points produce a curve smoothing estimated one by one than on identifying outliers, and finally achieve the estimated value outliers replace excluded error data. The experiments show that the actual results and the experimental simulation match to improve measurement accuracy. 3, through in-depth analysis system power consumption, choose the low power consumption of the chip, does not affect the measurement accuracy while simplifying data processing algorithms, signal processing hardware circuit time-sharing turned on and off and the MCU Sleep mechanism to achieve lower power consumption purposes, experiments show that this approach is feasible. Based of the key technologies of the time difference ultrasonic flowmeter experimental prototype and tested it, the results show that the experimental prototype to meet \
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