According to the problems of complex operation and low accuracy of the existing methods for measuring the damage caused by liquid lock, a high precision injection device and corresponding methods for measuring the damage caused by liquid lock are designed, and a method for evaluating the damage caused by liquid lock is formed. The results show that the designed injection device and test method are more precise and practical. The damage of liquid lock mainly occurred in the interval with relatively high water saturation, and the damage rate of permeability gradually increased with the increase of water saturation, all of which is more than 50%,It presents "S" curve shape, and the lower the permeability, the more obvious the "S" shape of the curve is. With the increase of permeability, the damage rate curve of liquid lock decreases in three stages with the permeability of 2.2×10_^-3μm_² and 15.5×10_^-3μm_² as inflection points. And the higher the permeability is, the smaller the damage degree is. The blocking radius of liquid lock increases with the increase of production, and increases with the increase of the damage rate of liquid lock at a certain output. According to the change curve of blocking radius, the evaluation criteria of liquid lock injury were established. The damage degree of liquid lock injury in the three areas of 0-27%, 27%-43% and more than 43% are respectively defined as low injury, medium injury and high injury. The corresponding blocking radius was 0-1.5m, 1.5-6m and more than 6m, respectively. Therefor timely measures should be taken to prevent the occurrence of liquid lock injury, and a reasonable gas well production system should be established. From the above, the experimental device and method designed in this paper have strong operability and reliable data, which provide an important basis for further study of reservoir damage and an important technical reference for oil and gas field development and reservoir protection.