Objective Thermal therapy by alkali metal provides an effective method for minimally invasive cancer treatment. In particular, with combined merits from both hyperthermia and chemotherapy, such method has a strong clinical practical value. However, it is a serious problem to monitor the thermal coagulation zone and evaluate the therapeutic effect after thermal ablation. In this work, certain image texture parameters of ultrasonic images with lager change are took out for therapeutic effect evaluation. Methods In the ultrasonic images of the normal pork tissues as well as those after the alkali metal ablation, 19 parameters, such as gray level histogram, gray level co-occurrence matrix, were analyzed with the method of image texture feature. Statistical results of 20 cases and parameters of the change rate were obtained. These parameters might be used as the basis to judge the tissue coagulation. Results Statistical data showed that the texture features: the mean of gray value and standard deviation in the gray histogram, the contrast of 0° and 45° in the gray level co-occurrence matrix, had a large variation after hyperthermia. Ultrasound image texture features could indirectly reflect the thermal ablation effect of alkali metal and be used as a criterion of thermal coagulation zone. When the gray value increased 50% and above, standard deviation increased 100% and above, the contrast in the gray level co-occurrence matrix increased 30% and above, the tissue could be judged as coagulation. Conclusions This paper provides an effective method for the therapeutic effect evaluation and real-time monitoring of the tumor ablation therapy by alkali metal.