The accuracy of the model for secondary electron yield (SEY) has a remarkable influence on the simulation result of multipactor threshold. A new combined phenomenological model for SEY was proposed based on the corrected Vaughan model and Furman model. It combines virtues of the latter two models by integrating corrected Vaughan model into Furman model for its calculation of yield of true secondary electron. The new model provides high flexibility and accuracy to fit experimental data of SEY as a function. For comparison, experimental data of silver and aluminum alloys were tested with the three models. It was found that the fitting accuracy has been improved by at least 10% under the circumstances of different incident angles of the original electron.