Abstract: Based on the experimental investigation for a standard sand and a coal ash,a elastoplastic model is pre-sented to simulate the stress-strain behaviour of cohesionlea seils under complex stress paths,in which, new fiowlaws and loading-unloading criterla are developed under the following assumption:1.the increment and direction ofplastic strain depend on not only the previous stress history and the current stress state,but also the direction of cur-rent strase increment.2.the stress ratio history is considered as a hardening parameter.It is worthwhile noting thatparameters of the proposed model can be determined conveniently by tests wlth simple stres paths。The validitv ofthis model has been verified through the comparison between predicted results and the experimental dsta under a va-riety of stress peths.