Abstract: The propagation of transientwave groups, focused on a point in time and space to produce waves with steepness, is simulated by resolving Laplace,duation using the higer-order boundary element method in the tune domain, in which the fully nonlinear boundary conditions and serni-mixed EulerLagrange method are used to track free surfazee.The fourtlrorder Runga Kutta method is used to comput the wave elevation and velocity potential on the free surface at each tune step.The 2nd-order Stokes analyical velocity is given at the incident boundary to generate the input wave.The unage Green function is applied in the present study so that the integration on the lateral surfaces and bottom are exduded.The experunental study on the focused wave groups with different wave slopes is carried out in awave flume.And the numerical solutions are compared with the ex perunental results.The characters of the nonlinear focused wave groups are studied here.