The invention discloses an autonomous navigation method of an AUV (Autonomous Underwater Vehicle) based on a FastSLAM (Simultaneous Localization and Mapping) algorithm. The autonomous navigation method comprises the steps that 1) the AUV acquires initial pose and position information through the GPS and a navigation sensor on the water surface; 2) predicting the pose and position and an environmental road sign of the AUV by adopting unscented particle filtering according to latest control variables inputted into the AUV and observation variables of the sensor; 3) generating a proposal distribution function for parameter adaptive adjustment by adopting fading adaptive unscented particle filtering, and sampling in the proposal distribution function; 4) associating the latest observation environment information according to each particle, and updating estimation for each characteristic by adopting unscented Kalman filtering; 5) performing resampling on a particle set by adopting an adaptive partial system resampling method; and 6) performing AUV positioning and map building. The autonomous navigation method can improve the particle sampling efficiency of the Unscented FastSLAM algorithm and reduce the degradation degree of the particles through improving the proposal distribution function and the resampling process of the Unscented FastSLAM algorithm, thereby enabling the consistency of AUV pose and position estimation and the accuracy of autonomous navigation to be greatly improved.