Researches　on　the　complex　behavior　of　power　electronic　circuits　and　systems　have　become　an　important　branch　in　power　electronics,　and　received　great　attention.　This　paper　reviews　the　progress　on　the　study　of　nonlinear　dynamics　of　power　electronic　circuits　and　systems,　and　presents　the　characteristics　of　these　circuits,　nonlinear　modeling　approaches,　bifurcation　characteristics,　and　routes　to　chaos.　In　particular,　the　key　points　of　the　applications　of　nonlinear　dynamics　study　in　practical　design　are　discussed　in　the　paper,　and　the　necessities　and　the　corresponding　strategies　of　controlling　bifurcation　and　chaos　are　demonstrated.　Furthermore,　some　future　research　directions　are　discussed　from　the　viewpoint　of　applications.