The invention discloses a weak target detection device and method for dual-band imaging correlation full-spectrum measurement. The device comprises an ultraviolet visible-light and infrared optical window, a large-field-of-view two-dimensional scanning rotating mirror, a common-aperture main optical system, an infrared imaging spectrum optical subsystem module, a visible and near-infrared imaging spectral optical sub-system module, an ultraviolet spectral optical subsystem module, a medium-wave large-field-of-view detector, a medium-wave infrared middle-view-field detector, an infrared non-imaging wide-spectrum spectral measurement system, a visible near-infrared large-field-of-view detector, a visible near-infrared middle-view-field detector, a visible near-infrared spectrum measurement system, an ultraviolet spectrum measurement unit, a multi-mode coordination information processing, and control module, a control module and a servo system. In addition, according to the method, a target background optical field is filtered; multi-scale coupling matching is carried out on distortion target radiation field multi-dimensional information; and multi-scale target detection information is utilized comprehensively to achieve objectives of precise target detection and identification and information inversion; and thus a problem that a weak target can not be detected in conventional remote-sensing detection can be solved.