This paper provides an overview of the algorithm for preventive control of transient stability in power systems. According to the analysis of the mathematical model, the process of the preventive control is presented. Besides, the methods are classified into three categories and various techniques including function transcription, optimal control theory, trajectory sensitivity, the One-Machine Infinite Bus Equivalence (OMIB), nonlinear programming and the computational intelligence optimization for the preventive control in power systems are summarized and evaluated. The simulation results on some common testing systems by the classic methods are shown for more distinct illustration. Finally, on the comments and discussions of the present methods, some existing problems such as variation of the initial value, the accuracy and the iterations in some algorithms are given, and the main development trend is pointed out for improving the preventive control in power system.