In this paper, lkeda equation for a nonlinear optical ring cavity is studied by numerical method. It is found that the topological structure, the way of bifurcation and its convergence rate and the period-window-structure depend on the parameters B and φ0 in long delay time limit. In short delay time limit, some anomalous period-windows and nonperiod-doubling bifurcations are revealed, and it is also discovered that the self-similar structure in chaotic bands is blurred in the short time limit.