This paper presents a non-contact probe with two laser displacement s ensors for measuring the inner dimension of the large workpieces on machine.The probe′s function can be analogized to a non-contact internal micrometer which has the ability to make the measuring program fast,non-destructive,precise and easily automatic.Before utilizing the probe to measure the inner dimension,it should be guaranteed that the optical axes of two lasers in the probe coincide.However,it′s generally difficult to ensure the discrete la sers meet the demand in practice.To solve the problem,this paper analyzes the influence of t he probe′ optic pose error on the detection precision,and gives the tolerance value through com puting the terminal data.At the same time,we design the corresponding laser optical coaxi al measurement and adjustment method based on the machine vision and a novel position transform .Finally,using the regulated and unregulated probes respectively to measure some standard gauge blocks,the results prove that the measurement and adjustment method is feasible,and the di fference between the measured value by the regulated probe and the standard value of the gauge is just 4μm.