In this study, ethylenediaminetetraacetic acid (EDTA), triethanolamine (TEA), and ethylenediamine (En) were adopted herein as additives or chelating agents in electroless copper plating, with formaldehyde as the reduction agent. Linear sweep voltammetry was successfully applied to analyze the potential shift of copper complexes and the adsorption capability of chelating agents on a surface. Moreover, the grain size and surface roughness of copper were investigated using atomic force microscopy (AFM). The experimental results for a dual-chelating-agent system indicated that EDTA plays an important role in chelating while the main effect of TEA is adsorption on copper surfaces to inhibit formaldehyde oxidation. Meanwhile, ethylenediamene is a prominent refining agent owing to its markedly higher adsorption strength on copper surfaces than formaldehyde and TEA. The analyses including linear sweep voltammetry, AFM, and XRD are effective to explore the effect of chelating agents and additives on electroless copper plating and deposits.