An oblique detonation wave (ODW) for a Mach 7 inlet flow over a long enough wedge of 30 degrees turning angle was simulated numerically using an Euler equation with one-step rection model. The fifth-order weighted essentially non-oscillatory (WENO) scheme was adopted to capture the shock wave. The numerical results show that three regions in the flow field behind ODW are defined: Zeldovich-von Neumann-Doering (ZND) model-like structure; single-sided, triple-point structure; and dual-headed, triple-point strucuture according to the wavelet structures. The first structure is smooth and straight. The latter two structures are very complicated. In the single-sided triple-point structure, all triple points facing upstream propagate dowanstream with almost the same velocities and have the character of temporal periodicity. Simultaneously, the triple-point traces are recorded to obtain cell structure of parallel straight lines. In the last structure, the triple points move down with two different velocities. The velocity of triple points facing downstream is obviously faster than that facing upstream, which leads to the periodic collisions of the triple point. This period has the character of temporal and spatial periodicity. The cell structure is inclining "fish scale" patterns due to the velocity component of the incoming flow tangential to the oblique detonation wave.