Generator maintenance scheduling used to prevent units aging， is important to ensure power system operating reliably. The mathematical model and algorithm of generator maintenance scheduling are summarized in this paper. In power market， system reliability and economic benefit of generating companies should be considered simultaneously in generator maintenance scheduling. Usually， generating companies first determine their maintenance scheduling separately， and then independent system operator（ISO） regulates maintenance scheduling according to system adequacy constraints. In this model， the former problem ensures economic benefit of generating companies considered as the independent economic entities; the latter guarantees power system operating securely. Generally the optimization problems are solved with help of heuristic methods， such as genetic algorithm（GA） and simulated algorithm（SA）， or mathematical ones containing integer programming algorithm and Benders decomposition method.