For a quantum system with multiple degrees of freedom or subspaces,loss of coherence in a certain subspace is intimately related to the enhancement of entanglement between this subspace and another one.We investigate intra-particle entanglement in two-dimensional mesoscopic systems,where an electron has both spin and orbital degrees of freedom and the interaction between them is enabled by Rashba type of spin-orbit coupling.The geometric shape of the scattering region can be adjusted to produce a continuous spectrum of classical dynamics with different degree of chaos.Focusing on the spin degree of freedom in the weak spin-orbit coupling regime,we find that classical chaos can significantly enhance spin-orbit entanglement at the expense of spin coherence.Our finding that classical chaos can be beneficial to intra-particle entanglement may have potential applications such as enhancing the bandwidth of quantum communications.