Galaxy distribution in clusters maybe affected by dynamical evolution of clusters and merging process of their member galaxies. In oreder to studey the effect, we study formation and evolution of galaxies in clusters by using N-body simulation. To identify galaxy size dark halos, we use the adaptive friends-of-friends algorithm (van Kampen 1995) at several red-shifts. At the same time, we treat galaxy merging and dark matter accretion to the galaxies by using the simple merging model. In this model we assume that galaxies have the merging cross section proportional to and if they encounter in small relative velocity (< Vmerge), they merge into one galaxy.