The invention discloses a high-speed contact network locator gradient detection method and an apparatus thereof based on video analysis. The method comprises the following steps of: a video acquisition step for acquiring operating environment video of a contact network in real time through a video acquisition device; a data processing step for performing fast detection and accurate location on a locator in the image, and respectively performing acquisition control, analysis and display of images by a multithread processing framework; and a step of obtaining the angle of the locator in an imaging plane coordinate system by a basic image processing operator after detecting out the locator successfully. In the detection method, a high resolution and high frame frequency photographic surveying device is mounted at the roof of a detection car so as to acquire the operating environment video of the contact network, a video camera is mounted in a manner of ensuring an imaging plane thereof to be perpendicular to a working direction of a train, and the angle measurement based on a cross axis of a roof section is transformed to be based on the cross axis of the imaging plane. The method and the apparatus provided by the invention can solve the defect that the prior locator gradient detection method can only detect the gradient when the detection car moves at low speed, and is poor in system flexibility and adaptability.