In this paper, the continuum self-consistent field theory(SCFT) is applied to study the structure and the interaction of the adsorption of symmetrical ABA polyampholytes(PAs) between two neutral planes. It is found that the amounts of all the conformations decrease with the increase of the charge fraction of polymer chain, and increase with the increase of the bulk salt concentration and become saturated at high bulk salt concentration. The effective interaction between the two planes presented a long-range repulsion. Splitting it into various components and relating with the dependence of the variations of the conformations on environment parameters, we try to find the origin of the total long-range interaction between the two planes. In this paper, the continuum self-consistent field theory (SCFT) is applied to study the structure and the interaction of the adsorption of symmetrical ABA polyampholytes (PAs) between two neutral planes. It is found that the amounts of all the conformations decrease with the increase of the charge fraction of polymer chain, and increase with the increase of the bulk salt concentration and become saturated at high bulk salt concentration. The effective interaction between the two planes presents a long-range repulsion. Splitting it into various components and relating with the dependence of the variations of the conformations on environment parameters, we try to find the origin of the total long-range interaction between the two planes.