The current centering and edge grinding equipment did not have the ability to get the parameters online，and manual grinding could cause the verticality of the positioning platform to exceed the tolerance. Therefore，it is particularly important to control the center deviation of the optical components and the concave aperture accuracy after optical centering. This paper designed a visual online testing device for centering. By adding the functions of online measurement of caliber and calculation of dragging edge feed amount，a visual detection device was designed and installed on the equipment to solve the problems of damaged surface smoothness of components，excessive verticality and caliber of the positioning platform caused by manual modifications. The actual test results show that the measurement accuracy of eccentricity，verticality，and concave diameter of the parts reaches 0.01 mm，which meets the practical application requirements of optical processing. By the visual online testing，the machining of the outer circle and positioning platform of the parts can be completed in one clamping process，upgraded the concave aperture accuracy of the components，reduced the manual grinding processes，and improved the product qualification rate and machining efficiency. A reliable and efficient solution for the centering technology of optical processing was provided.