The heteroclinic bifurcation and chaos in Josephson system subjected to an amplitudemodulated force are discussed. By using Melnikov method

the bifurcation conditions of chaotic motion are obtained. The effects of the bifurcation parameters on dynamical behaviors are also studied by using numerical simulations. Numerical simulations including bifurcation diagram of the fixed points

phase portraits

bifurcation diagrams of the system

not only show the consistence with the theoretical analysis but also exhibit the more new complex dynamical behaviors. The results of theoretical analysis and numerical simulations show that the amplitude f and the frequency Ω of the amplitudemodulated force play very important role for dynamics of the system.