The invention discloses a stray current simulation modeling method based on multi-train operation conditions, and relates to the field of stray current simulation modeling. According to the method, the stray current distribution characteristic is used; a 'steel rail-drainage network-buried metal-ground 'four-layer earth screen structure model conforming to actual subway line characteristics is utilized; a train and a traction substation are regarded as direct-current sources to inject current to the ground together; based on this, a distribution model of the electrical quantity of the earth screen under the action of a single injection source is deduced by using a micro-element method, and then the action results of the injection sources are superposed to obtain the distribution conditionof the electrical quantity on the whole line, so that the whole line stray current and the steel rail potential value obtained by simulation more accord with actual values. The method solves the problems that a traditional stray current distribution model is only driven by a single train and only supplies power to one or two substations, the model structure is simple, boundary conditions are greatly different from actual conditions, and large errors exist between simulation results and measured values.