Abstract: During focused ultrasound hyperthermia, the precise measurement and assessment of the internal focal temperature of tissues are of significant importance for treatment. To realize non-contact measurement of the internal focal temperature during ultrasound irradiation, a scheme based on inverting the post-focal transmitted acoustic pressure along the acoustic axis was proposed. Combined with the acoustic-thermal field coupling theory, relevant simulation calculations were performed to develop an experimental scheme for non-invasive evaluation of focal tissue temperature during ultrasound hyperthermia. Experiments were carried out using gel phantoms, fresh fat, pork tenderloin, and other tissues. The results indicated that, compared with the simulation-calculated results, the average errors of focal temperature with the method based on detecting the post-focal transmitted acoustic pressure were 6.25%, 1.53%, and 8.13%, respectively; compared with the results of thermocouple verification experiments, the average errors were 8.30%, 7.56%, and 9.15%, respectively. The results were well-matched, and non-contact measurement of the internal focal temperature could be achieved without protein denaturation in tissues. This provides a basis for planning the dosage administration of ultrasound therapy and holds clinical application prospects.