A high-precision angle sensor and a new method for calibrating precision angle sensor absolutely without any accurate reference instruments are described. Two angle sensors with compensate devices which compensating thermal drift of the light source are developed and calibrated by themselves. The measurement ranges of two angle sensors are 180″, and the resolutions of two angle sensors are 0.003″ and 0.004″, respectively. The repeatability error of the evaluated mean sensitivity was improved to 0.015% by compensating device. The repeatability of the calibrated linearity error was reduced to 0.015″.