The invention relates to a smart phone user indoor positioning method based on terrestrial magnetism auxiliary WiFi. The method comprises an offline stage and an online stage. The offline data acquisition stage comprises dividing an area to be positioned into small grids according to a building planar map; acquiring the data of the area to be positioned by using a smart phone, wherein a smart phone user holds the smart phone to acquire WiFi signal intensity and terrestrial magnetism intensity data for some time at the center of each grid; averaging the data acquired in each grid and constructing and storing an offline fingerprint database in the smart phone. The online positioning stage comprises steps of: initializing a position, computing the weight of each fingerprint, selecting k fingerprints with the highest weights, and using the weighted positions of the k fingerprints as an initialized position; holding the smart phone to rotate and initializing a sensor; updating a Rss weight and a terrestrial magnetism weight; updating the weights; and estimating the position. The method may achieve high indoor positioning precision with the smart phone.