A new displacement measurement system is described in this paper according to the basic principles of traditional lasertriangulation method. The range of the traditional measuring method is enlarged by measuring in sections. Three independent CCDs, which are distributed uniformly along the optical axis, are used to achieve subsection measurement. The planemirror is regarded as a virtual detector. When imaging beam is reflected by the plane mirror, the beam is imaged on theCC D. The designed system is equivalent to add a CCD. The feasibility of the displacement measurement system is verifiedby the experiment. A range of the traditional measuring method is enlarged by measuring in sections. Three independent CCDs, which are distributed uniformly along the optical axis, are used to The subsection is measured as a virtual detector. When the imaging beam is reflected by the plane mirror, the beam is imaged on the CC D. The feasibility of the displacement measurement system is verified by the experiment