Embodiments of the present invention relate to the field of video monitoring and provide a method, an apparatus, and a system for acquiring a visual angle, so as to acquire an accurate visual angle value. The method for acquiring a visual angle includes: receiving, by a central processing unit CPU of a camera, angle information that is sent by an accelerometer sensor arranged on the camera; converting, by the CPU, the received angle information to a visual angle value; sending, by the CPU, the visual angle value to a server, so that a client receives the visual angle value forwarded by the server. The embodiments of the present invention are applicable to a video monitoring scenario.