The invention relates to a system and method for detecting the relative position and the speed of an elevator car. The system comprises a shaft, the elevator car, reference objects, an imaging device used for continuously shooting the reference objects, and a controller electrically connected with the imaging device. The elevator car and the reference objects are located in the shaft, the imaging device is arranged on the elevator car, and the reference objects are arranged along the moving track of the elevator car. The imaging device and the elevator car move simultaneously, the actual position of the car can be truly and reliably detected by conducting shooting and image recognition on the reference objects in the shaft, the detection deviation caused by skidding of a rotary component is avoided, and the detection precision is improved; the reference objects are shot through the imaging device, the reference objects do not need to be specially coded or printed with special images, application is easy and convenient, cost is low, installation and adjustment are convenient, and the application range is wide.