The adsorption of weak polybase on oppositely charged planar surfaces has been investigated numerically by using the self-consistent field theory(SCFT). Particular attention was paid to the interplay of monomer-surface electrostatic and non-electrostatic interactions in the adsorption behaviors of weak polybase. In this study, the strength of monomer-surface non-electrostatic interactions was set to be no more than the thermal energy kBT. It was found from the numerical study that in the regime of low surface charge density of the substrate and low p H or high bulk degree of ionization, both the screeningenhanced and screening-reduced salt effects emerge. On the contrary, in the opposite regime, only the screening-reduced salt effect was observed. Moreover, the overall charge neutrality inside the adsorption layer was analyzed. The underlying mechanism governing the adsorption behaviors of weak polybase on oppositely charged surfaces was elucidated. The adsorption of weak polybase on oppositely charged planar surfaces has been investigated numerically by using the self-consistent field theory (SCFT). Special attention was paid to the interplay of monomer-surface electrostatic and non-electrostatic interactions in the adsorption behaviors of weak polybase . In this study, the strength of monomer-surface non-electrostatic interactions was set to be no more than the thermal energy kBT. It was found from the numerical study that in the regime of low surface charge density of the substrate and low p H or high bulk degree of ionization, both the screeningenhanced and screening-reduced salt effects was emerge. On the contrary, in the opposite regime, only the screening-reduced salt effect was observed. Moreover, the overall charge neutrality inside the adsorption layer was analyzed. The underlying mechanism governing the adsorption behaviors of weak polybase on oppositely charged surfaces was elucidated.