This study proposes a two-stage path planning method for the path planning task of the inner wall operation of a mobile robot in multi-room. In the first stage, for the sensor failure caused by dust or fog in the environment during wall operation and incomplete path planning when there are many exits in a room, the study proposes a start-point automatically selected wall following path planning method, which is based on grid maps to generate the wall following paths offline. In the second stage, for the dynamic obstacle avoidance problem during point-to-point path planning, it proposes a point-to-point path planning method based on the prioritized experience replay soft actor critic (PSAC) algorithm, which introduces the prioritized experience playback strategy in the soft actor critic (SAC) to achieve dynamic obstacle avoidance. The comparison experiments of wall following path planning and dynamic obstacle avoidance are designed to verify the effectiveness of the proposed method in the indoor wall following path planning and point-to-point path planning.