A lot of numerical investigation of equations of rf-biased Josephson junctions is carried out, in which the interference term is included in current-phase relation. Chaotic behavior, sequence of period-doubling bifurcations, inverse sequence of chaotic band and intermittent chaos are found seperately in various parameter regions. The convergent factor δ n of 2n Psequence and the ratio Φ(k)/Φ(k+1) are calculated, where Φ(k) is the average height of the peaks corresponding to 2kP in the power spectrum. We also study the symmetry possessed by period solutions and its relation to the nature of approach to chaos