Fast-growing economy is driving the rapid urbanization of China. An e-bicycle, also known as an electric bicycle, is one of the major trip modes in the third and fourth-tier cities of China which is quite different from big cities such as Beijing and Shanghai. In this paper, a discharge model of e-bicycle mixed traffic flows is proposed. With the discharge model of mixed traffic flow, an average delay formula of mixed traffic flow is developed. The relationship between the average delay and cycle length is analysed, for the cases of pure motor vehicles delay and e-bicycle mixed traffic delay, respectively. A practical traffic signal setting method is proposed for controlling the e-bicycle mixed traffic flow. It demonstrates that the optimal cycle length obtained from the proposed method is normally larger than that got from the Webster method, which complies with the field application and fits the real traffic circumstances.