A process of nonlinear three-dimensional rupture of thin liquid films is numerically analyzed for the first time, With the rupture time being successfully calculated, it has been possible to develop a more complete rupture theory for thin liquid films, In contrast to the linear analysis indicating the shortest rupture time of thin liquid films to be the same for both two- and three-dimensional rupture, the nonlinear analysis reveals that the latter proceeds faster than the former, In particular, among all three-dimensional disturbance modes, the symmetric one makes the thin liquid films rupture fastest, It is concluded that the rupture process develops at a point rather than along a line on thin liquid films.