•A model that considers PS to describe pedestrian movement on stairs is proposed.•The personal space (PS) is composed of four arcs which belong to four circles.•Dynamic characteristics of PS and its specifications were obtained from experiment.•A simulation was hold under the obtained parameters.•Fundamental diagram according to different na/nb was analysed. This paper presents an enhanced model that considers the specifications of personal space to describe uni- and bi-directional pedestrian movement on stairs. The shape of the personal space of each pedestrian is regarded as an oval shape, which is composed of four arcs, to precisely quantify movements. Specific models that facilitate the simulation of movement include adjustments to individual speeds based on the proximity of other members, conflict avoidance, overtaking, and direction finding. By implementing these parameters in the simulation, basic data concerning these movement behaviours were collected from the experiment, which was carried out at one a Shanghai subway station. Twenty-four young college students participated in this experiment. Numerical simulation results for a stochastic case under those parameters were obtained. The fundamental diagrams and moving behaviours according to different proportions of ascending and descending pedestrians are analysed and discussed. The results indicate that the simulation platform for personal space can serve as a useful tool to evaluate pedestrian movement on stairs.