The invention provides an indoor floor positioning method based on a smart phone, and belongs to the technical field of indoor positioning. The method comprises the following steps: firstly, judging whether a user enters a to-be-positioned building through an ''entry'' detection algorithm, and if so, endowing the user an initial position of floor positioning: first floor; then, judging whether theuser goes upstairs or downstairs according to a going upstairs or downstairs behavior detection algorithm, calculating the variable of the floor when the user goes upstairs or downstairs, and obtaining the current floor of the user in combination with the initial position of floor positioning. In addition, space users are grouped, the positioned user uploads position information for position sharing, so that all users can obtain new initial positions of floor positioning, and the floor information of the user at any moment can be known in combination with the detection of going upstairs or downstairs and the vertical movement estimation. By adoption of the indoor floor positioning method, high-precision and high-availability indoor positioning technology is achieved, indoor high-precisionpositioning is achieved, and the indoor position service and application are promoted.