This paper presents the basis of acoustic method used for temperature field measurement of seafloor hydrothermal vents. Study on the refracted propagation path of sonic waves in seafloor nonuniform temperature field with Fermat’s theory and by variational calculation, and is numerically calculated in the model’s temperature field. Experimental research is performed to exactly rebuild the temperature fields around hot springs on floor of Lake Qiezishan, Yunnan. The accuracy of time of flight estimation has been improved based on the technique of bending compensation of propagation paths of acoustic signal. At the same time, by comparison with two temperature fields, the max absolute error, the max relative error and the root mean square error are given. It shows that the bending compensation of propagation paths of acoustic signal technique can be applied to temperature field measurement detector around seafloor hydrothermal vents. It also has a good accuracy.