The invention discloses a robot positioning method fusing an RGBD depth sensor and an encoder. The method comprises the following steps: firstly, establishing a guidepost database in a robot moving region, wherein the guidepost database comprises a guidepost image and corresponding robot position coordinates; in the robot moving process, positioning a robot position matrix Twe(t) based on the encoder; and meanwhile, performing positioning based on the RGBD depth sensor; if performing positioning based on the RGBD depth sensor successively, calculating a transformational matrix according to the robot position matrix Twe(t) positioned based on the encoder and the position matrix Twv(t) positioned based on the RGBD depth sensor; setting the robot current position matrix as Twv(t); and if not positioning successfully, correcting the positioning error on Twe(t) through the transformational matrix to obtain the current position matrix. According to the invention, the positioning error of the encoder is corrected based on the GBD depth sensor, so that the positioning precision and the robustness of the robot are improved.