A new special-purpose optical coordinate measurement machine has been developed with the cylinder coordinates to solve the problem of testing aspherics with full aperture in the stage of grinding and pre-polishing .A full aperture measurement was made by testing several meridians in the point by point manner. In the aspect of hardware, the system is composed mainly by an ultraprecise air guide-way, realizing the linear motion, and a graduator, realizing the rotary motion. In the aspect of software, the mathematical model of the system was analyzed and a new algorithm for the full-aperture testing of rotationally symmetric aspherics was built. The testing software and data-processing software are written on the VC++6.0 and Matlab6.5 platform respectively. The maximum measurement range of the system is 600mm, the maximum sag: 25mm, the minimum sampling step, 1 mm and the accuracy is better than 1um in full scale, after the compensation of the systematic errors. The requirement in the grinding and pre-polishing process for the test of aspheres has been satisfied. The real experiments indicate: the system runs well and has a good repeatability and accuracy.