Abstract: In order to eliminate the periodic dislocation and improve the measurement speed, a method named asymmetric combined cycle-encoding is presented. This method replaces the sinusoidal phase-shifting with trapezoidal for optimizing measurement speed. The traditional periodic dislocation is solved by building the non-symmetrical correspondence between two kinds of codes. The inherent error of cyclic code is eliminated by modify the period of cyclic code and trapezoidal phase shifting intensity code. The measurement speed is improved significantly. Experimental results show that the presented method in this study greatly reduces the measurement error. The measurement error is less than 1.7 mm in the range of 1000 mm.