  We study the non-canonical symplectic structure, or K-symplectic structure
inherited by the charged particle dynamics. Based on the splitting technique,
we construct non-canonical symplectic methods which is explicit and stable for
the long-term simulation. The key point of splitting is to decompose the
Hamiltonian as four parts, so that the resulting four subsystems have the same
structure and can be solved exactly. This guarantees the K-symplectic
preservation of the numerical methods constructed by composing the exact
solutions of the subsystems. The error convergency of numerical solutions is
analyzed by means of the Darboux transformation. The numerical experiment
display the long-term stability and efficiency for these methods.
