Peak searching algorithms are the key issue in alignment automation between a laser diode(LD) and a single-mode fiber(SMF).The coupling characteristics at the fiber end are analyzed theoretically,and the parabola approximation algorithm is developed for fiber alignment automation.The principle of the parabola approximation algorithm in fiber alignment automation is discussed in detail.The experimental results are presented at last.Compared to traditional hill-climbing algorithm,the cycle time for alignment automation with parabola approximation algorithm is shortened notably.The main reason is that the sample points are reduced greatly.