Abstract: In order to analyze the trapping efficiency of multi-layer particles in a focused beam, the T matrix of the double-layer spherical particle was deduced. The trapping force on double-layer spherical particles was numerically calculated by means of the vector diffraction integral combining the T matrix method and the Maxwell stress tensor integral. Effect of the refractive index and size of the inner layer on trapping efficiency was discussed in detail. The focused beam can trap the double-layer spherical particles only when the refractive index of the inner layer is appropriate. The maximum backward trapping efficiency will increase at first and decrease to zero finally when the refractive index increases. For hollow particles, the bigger the hollow is, the weaker the trap is. Besides, the trap formed by plane wave is stronger than Gaussian beam. The calculation method of the force on double-layer spherical particles can be expanded to the case of multilayer complex particles.