Abstract: This paper introduces the AirMatrix airspace planning concept as an urban low-altitude airspace planning scheme to realize the efficient and safe operation of eVTOL aircraft in urban low altitude airspace, and to solve the problems of complex and variable airspace, complicated obstacles, low altitude flight, noise and meteorology faced by its path planning, thus promoting the rapid arrival of urban air mobility era. The AirMatrix airspace is divided into four-dimensional blocks according to the urban low-altitude operation characteristics of eVTOL. In this paper, the rapidly-exploring random trees (RRT) algorithm, the improved A* algorithm, and the particle swarm optimization (PSO) algorithm are selected to perform a comprehensive analysis and simulation verification in 3D terrain. The results show that the RRT algorithm has the fastest search rate, the A* algorithm has the best path planning quality, and the PSO algorithm is lacking in both path planning length and search rate. Therefore, the A* algorithm is considered to be more suitable for low-density urban airspace path planning than the RRT and PSO algorithms.