Harmony search algorithm is a new intelligent optimization algorithm. By repeatedly adjusting the solution variables in harmony memory, the function converges to its optimal solution with increased iterations and completes the optimization. The algorithm is simple in concept, less adjustable parameters, easy to implement. In this paper, the origin of harmony search algorithm and the basic idea are given. We give the basic steps and processes of harmony search algorithm, and analyze harmony memory considering rate and pitch adjusting rate that effects on the algorithm. The difference between harmony search algorithm and genetic algorithm is compared. Furthermore, the applications and research trend of harmony search algorithm are pointed out.