An infrared-visible confocal optical system for simultaneous extraction of human fingerprint and finger vein images is designed, which consists of ten spherical lenses with system focal length of 10 mm, total field of view of 34° and F number of 2.4. In order to reduce the instrument volume, the conjugate distance of this system is controlled within 120 mm. After optimization by the ZEMAX software, the design results show that the lights with different wavelengths strictly image on the same image plane. The value of modulation transfer function at a spatial frequency of 164 lp/mm required by this system is greater than 0.4. The sizes for all defocused spots in view field are smaller than the smallest pixel size of the image device and the distortion is less than 1%. The tolerance analysis of the system shows that this design meets the manufacturing requirements.