The variant Boussinesq equations were studied based on the multisymplectic theory in Hamilton space. The multisymplectic Preissmann method was reviewed,and a semiimplicit scheme with certain discrete conservation laws was constructed to solve the first order partial differential equations derived from the variant Boussinesq equations. The results of numerical experiment for soliton solution of the variant Boussinesq equations were obtained,which show that the multisymplectic Preissmann method is an efficient algorithm with excellent long time numerical behaviors.