The phenomena of bifurcation and chaos in a current mode controlled Buck converter with switching delay were explored.The mathematical model was developed.Using the ideal DC input voltage as a variable,diagrams of bifurcation and chaos were given in regard to the parameters of an ideal switch and three typical switching delay through computer simulation.The Poincare section and time domain graphs about inductive current and capacitor voltage were provided.The experimental analysis shows that with the increase of switching delay time,the bifurcation will be intensified and even lead system to instability.