Abstract: Mixed Weibull distribution is usually used to model reliability of products with more than one failure modes. Due to the difficulty of estimation of distribution parameters, it has not been widely used. In this paper, a mixed model involving two Weibull distributions is considered; and its parameters estimation model is established using nonlinear least square theory. Levenberg-Marquardt algorithm is used to solve the optimization problem. To reduce iterative time, the estimator from graphical method is used as initial value. A numerical example is employed to illustrate the feasibility and accuracy of the proposed method.