The invention discloses a low coherence light interference measuring method and device of mirror spacing of multi-mirror lens set. The method comprises the following steps: producing first and secondlow coherence light; arranging a wedge prism set on a first light path, wherein the wedge prism set consists of a first wedge prism and a second wedge prism which have the same wedge angle; arrangingan optical flat plate and a measured multi-mirror lens set on the second light path; adjusting the measured lens set to a proper position; continuously moving to the second wedge-shaped prism along the edge surface of the wedge angle until reflected light on each mirror of the measured lens set and reflecting light on the other edge surface of the wedge angle of the second wedge-shaped prism sequentially form interference stripes on a receiving surface of a CCD camera; and calculating the space between adjacent mirrors on a central axis of the measured multi-mirror lens set according to the position number of the produced two adjacent interference stripes during the moving of the second wedge-shaped prism. With the adoption of the method and the device, the noncontact nondestructive measurement of the space between mirrors of the multi-mirror lens set is achieved; the reaction is sensitive; and the measurement accuracy is high.