The action time of relay contactors are not the same, which is likely to cause competition risk phenomenon leading to abnormal working of the control circuits. A practical relay control circuit function simulation and detection method is introduced, where KEIL and PROTEUS software are used to establish the relay model which puts forward the relay action contains four different delay time. A relay control circuit model is established based on an on-site case, an algorithm closer to the actual working condition is presented. By functional simulation, it is proved that the model can simulate the function of control circuit and detect the competition risk phenomenon. The method is simple, effective and intuitive, and it can be used for performance analysis of electrical control circuit based on relays.