Abstract: To improve simultaneous localization and mapping (SLAM) in indoor environments, the cellular automata (CA) is introduced into the iterative process of traditional SLAM algorithm and "SLAM-CA-relocation" closed-loop mechanism is established. Based on the characteristics of the regular indoor environment and a priori map in most mobile robot applications, the indoor SLAM problem is further studied. In the simulations and experiments in artificial indoor environments, the features of wall, exit, doors and right-angle parts become more clear, the problem of "through walls" is solved to some extent, the mapping quality is improved, the localization precision is increased, and the feasibility of path planning is also enhanced.