A terahertz wave security inspection system, comprising: an information acquisition device comprising a terahertz wave imaging mechanism configured to generate a terahertz wave image of an object to be detected and a visible light imaging mechanism configured to generate a visible light image of the object to be detected; and a data processing device in data communication with the information acquisition device and configured to: acquire the terahertz wave image of the object to be detected provided by the terahertz wave imaging mechanism and the visible light image of the object to be detected provided by the visible light imaging mechanism, determine whether a suspected item exists in the object to be detected or not based on the terahertz wave image and the visible light image, and if it is determined that a suspected item exists in the object to be detected, determine whether the suspected item is a prohibited item or not based on the visible light image and the terahertz wave image; the system being chracterised in that: the visible light imaging mechanism is located at an inner side of a virtual cone with a center of rotation of a speculum of the terahertz wave imaging mechanism as a vertex, a normal direction of field of view as a centerline, and a vertex angle of view of α/3, wherein α is a field of view of the terahertz wave imaging mechanism, and the terahertz wave security inspection system further comprises a housing in which the terahertz wave imaging mechanism is located, and the housing is provided with a window, a terahertz wave emitted by the object to be detected is transmitted through the window and received by the terahertz wave imaging mechanism to generate the terahertz wave image, and the visible light imaging mechanism is located on the window. an information acquisition device comprising a terahertz wave imaging mechanism configured to generate a terahertz wave image of an object to be detected and a visible light imaging mechanism configured to generate a visible light image of the object to be detected; and a data processing device in data communication with the information acquisition device and configured to: acquire the terahertz wave image of the object to be detected provided by the terahertz wave imaging mechanism and the visible light image of the object to be detected provided by the visible light imaging mechanism, determine whether a suspected item exists in the object to be detected or not based on the terahertz wave image and the visible light image, and if it is determined that a suspected item exists in the object to be detected, determine whether the suspected item is a prohibited item or not based on the visible light image and the terahertz wave image; the system being chracterised in that: the visible light imaging mechanism is located at an inner side of a virtual cone with a center of rotation of a speculum of the terahertz wave imaging mechanism as a vertex, a normal direction of field of view as a centerline, and a vertex angle of view of α/3, wherein α is a field of view of the terahertz wave imaging mechanism, and the terahertz wave security inspection system further comprises a housing in which the terahertz wave imaging mechanism is located, and the housing is provided with a window, a terahertz wave emitted by the object to be detected is transmitted through the window and received by the terahertz wave imaging mechanism to generate the terahertz wave image, and the visible light imaging mechanism is located on the window. the visible light imaging mechanism is located at an inner side of a virtual cone with a center of rotation of a speculum of the terahertz wave imaging mechanism as a vertex, a normal direction of field of view as a centerline, and a vertex angle of view of α/3, wherein α is a field of view of the terahertz wave imaging mechanism, and the terahertz wave security inspection system further comprises a housing in which the terahertz wave imaging mechanism is located, and the housing is provided with a window, a terahertz wave emitted by the object to be detected is transmitted through the window and received by the terahertz wave imaging mechanism to generate the terahertz wave image, and the visible light imaging mechanism is located on the window.