Abstract: In order to provide high quality signal for ultrasonic flowmeter,the transducer system of ultrasonic flowmeter is analyzed in theory.Transceiving (transmitting and receiving) voltage sensitivity is proposed to characterize the synthetically transmitting and receiving performance of the transducers.Based on the equivalent networks theory,the characteristics of transmitting transducer and receiving transducer are calculated,and then the characteristics of the transducer system are given.By the analysis of the characteristics of the transducer system,the best design of transducers can be got at all operating frequencies.By using the above theory,the transducer system suitable for ultrasonic heatmeter is also designed,and the manufacture and experiment of the transducers are introduced.The results show that the heatmeter can get the optimal signal at all operating frequencies and also prove the validity of the theory used to design the transducers of the ultrasonic flowmeter system.