Objective Temperature monitoring is essential for hyperthermia guidance, treatment efficacy and thermal dose control. The objective of this study is to explore a new method for noninvasive temperature estimation of microwave hyperthermia based on ultrasound attenuation coefficients (UAC). Methods In this study, water bath heating experiments were performed to fresh in vitro porcine liver tissues, and the original ultrasonic echo signals at different temperatures were collected. The UAC of porcine liver tissues at different temperatures were analyzed, and the correlation between UAC and temperature was derived for temperature estimation in microwave heating experiments. Results The correlation between UAC and temperature was: UAC = 0.513×Temperature-0.80. Temperature estimation based on UAC for microwave hyperthermia had a smaller error (<5℃) in="" the="" temperature="" range="" of="" and="" a="" bigger="" error="">10℃) in the temperature range of >50℃. Conclusions The UAC might be used for noninvasive temperature estimation of mild hyperthermia. It was difficult to accurately estimate the temperature because of the heterogeneity of temperature distribution in microwave hyperthermia. It might be a potential approach for detecting thermal coagulation zones based on the difference between the UAC of normal and coagulated tissues.