To study the dynamic pressure characteristics of low permeability reservoir, a mathematical model of tri-linear flow for fractured horizontal well considering joint-network is established. Dimensionless bottom hole pressure for this model is presented considering wellbore storage and skin factor using Laplace transform and Duhamel's principle, then dynamic pressure curves for fractured horizontal well are drew using Stehfest’s numerical inversion method. Elements that may affect pressure curves are studied and the results are analyzed. The results of the study show that storage capacity ratio mainly influences the hollow’s width and depth and the time of its appearance in the pressure derivative curve; cross flow coefficient mainly decides the hollow’s position; the fractured conductivity mainly influences the appeared time of bi-linear flow and the position and characteristics of the first hollow; the width of the inner region mainly affects the time of duration of linear flow in inner region.