Pipeline gas transportation plays a key role in the energy and industrial fields. Gas leakage is a problem that cannot be ignored and may lead to serious accidents. When a pressurized gas pipeline leaks, the gas is ejected from the leakage hole to form turbulence, which generates ultrasonic waves. Due to the strong directionality of ultrasonic waves, it is possible to use ultrasound for leakage positioning. In this paper, a positioning method based on ultrasonic energy attenuation is proposed. According to the sound energy attenuation model, the gas leakage localization problem is transformed into a mathematical model of nonlinear overdetermined equations, and the gradient descent-enumeration joint method is used to realize the location of gas leakage. And an acquisition system for leakage signal is designed according to the leakage characteristics of pressurized gas pipelines, which is composed of ultrasonic receiving sensors, amplification filtering, and signal processing circuit. In the end, the influence effects of different leakage situations and test conditions on the positioning accuracy were analyzed.