Abstract: Wave impedance inversion is non-linear inverse problem. In recent years, great efforts have been made in the research and application of the nonlinear inversion problems and more and more new non-linear inversion methods have emerged. This paper adopted an improved particle swarm optimization, i.e. an adaptive particle swarm optimization for the wave impedance inversion. The adaptive particle swarm optimization is based on the swarm intelligence theory, and this method combines three possible directions of movement with rights for global optimization. The method has faster search speed and strong ability of global optimization. The paper applied this method in function test and wave impedance inversion. The results show that the adaptive particle swarm optimization algorithm is a global optimization algorithm with strong adaptability. It is feasible and effective for wave impedance inversion problem.