Abstract: A procedure with vortex lattice method is developed to design and analyze winglets.It can determine the lift, induced drag, pitching and bending moments of the wing/winglet configuration.In this procedure a constant roll-angle method is adopted to divide the spanwise lattice and to determine spanwise location of control point, and a combined flow field method is applied to calculation of the induced drag.The characteristics of a swept wing with various configurations of winglets comprising five fins with different cant angles are analyzed, The effects of different winglets on the characteristics of the wing are discussed.A semimodel of swept wing is utilized in wind tunnel tests and the winglet is installed at the tip of the wing. The six component forces of the model are measured and the data of the pressure distribution on the wing surface are also obtained.Comparison between the results of calculation and the experimental data are shown in a good approximation. In preliminary design and choice of the winglet the present procedure can be applied to determining the win-glet geometry and cant angle required to minimize the induced drag.