The invention provides a long interference optical cavity tuning device and method based on a self-compensating translation axis. The device comprises a laser, sliding tables, first and second translation axis interference measurement modules, an imaging lens, an image sensor and a computer, wherein the sliding tables are mounted on a precision guide rail; the sliding tables can move between firstand second interference optical cavity endoscopes along a preset light path; the first and second translation axis interference measurement modules are arranged on the sliding tables; each translation axis interference measurement module comprises a first small collimation hole, a beam splitting prism, a second small collimation hole and first and second interference measurement module endoscopes, which are sequentially arranged on the preset light path; the first and second interference measurement module endoscopes are arranged at both sides of the beam splitting prisms and positioned on corresponding interference light paths; the interference light paths of the first and second translation axis interference measurement modules are perpendicular to each other; the imaging lens is used for carrying out imaging on interference images of the first and second translation axis interference measurement modules; the image sensor is used for outputting digital images of the interference images; and the computer is used for processing the digital images and feeding back a self-compensating multi-axis precision regulation strategy according to a processing result.