Abstract: In the frequency range 2-9.3 MHz and tempreature range 5-40℃,ultrasonic attenuation coefficients of five normal tissues and three abnormal tissues excised from five people were measured in vitro.Pulse transmission technique was used.The dependence of ultrasonic attenuation upon frequency and temperature was considered and more attention was paid to ultrasonic attenuation of abnormal tissues.The ultrasonic attenuation coefficients of normal and abnormal tissues were compared.The results show that the ultrasonic attenuation in abnormal tissue is higher than that in normal tissue.Several conclusions on the experimental results were given.