Summary: The multi-symplectic Hamiltonian formulation for nonlinear improved modified Boussinesq (IMBq) equation is considered, and the Preissman multi-symplectic integrator is deduced via implicit midpoint rule. Through eliminating middle variables, we get a new scheme which is equivalent to the Preissman multi-symplectic integrator. Moreover, we prove that it satisfies discrete multi-symplectic conservation law. In the end, we carry out some numerical experiments to illustrate its validity.