To investigate the invasion effects of electric bicycles on motor vehicle traffic flow at an urban signalized intersection, a model was developed for the heterogeneous traffic flow of motor vehicles and electric bicycles. This model introduces the gap force, car-following force and repulsive forces into the original social force model to describe the characteristics of the heterogeneous traffic flow, and was calibrated and validated by using real data. Then, the influences of the the number of electric bicycles in queue and arrival rate of the electric bicycles on the flow rate and average speed of the motor vehicle traffic flow were analyzed. The calibration results showed that the e_MAE, e_MARE and U values for the flow rate and average speed calculated by the proposed model were less than 12%, which indicates that the proposed model can reflect the characteristics of the heterogeneous traffic flow with low errors. When the number of queuing electric bicycles is more than 20, appropriate traffic organization and control methods should be adopted to reduce the conflicts between electric bicycles and motor vehicles. Allowing electric bicycles to pass 2 or 3 seconds ahead of green signal or moving forward the stopping line for them may increase the capacity of the intersection for motor vehicles.