We present hybrid simulations of reconnection layer at the flank magnetopause, where a large plasma flow speed is present in the magnetosheath. It is found that there exists a threshold flow speed v* such that for the magnetosheath flow speed vsv*), the rotational discontinuity with a larger field rotation angle exists on the magnetosheath (magnetospheric) side of the reconnection layer. The threshold speed is found to be v*=vAm-vAs, where vAm(vAs) is the Alfv¿n speed on the magnetospheric (magnetosheath) side of the reconnection layer. Furthermore, for vs≪v*, the rotational discontinuity on the magnetosheath side is very thin, and an accelerated high-speed flow is located earthward of the rotational discontinuity, as observed at the dayside magnetopause. For vs~v*, the magnetic field transition region is thick, and the accelerated flow is present in the entire field transition region, as observed at the flank magnetopause. ¿ American Geophysical Union 1994