Abstract: The wire & arc additive manufacturing (WAAM) of cold metal transfer (CMT) for high-strength marine steel was studied. By analyzing the influence of different proportion of shielding gas on the morphology of single-pass single-layer, the results showed that the wetting capacity of single-pass single-layer increases with the increase of CO₂ in the shielding gas. And a full-period cosine function prediction model was established, which could accurately predict the section profile of single-pass single-layer under 80% Ar + 20% CO₂ shielding gas. According to the forming characteristics of single-pass multi-layer, a prediction model for single-pass multi-layer uplift distance h was established based on the area relationship and geometric morphology. The relative error of the predicted value of uplift distance h was less than 3.50%. By establishing the uplift distance model, it provided theoretical support for single-pass multi-layer of wire & arc additive manufacturing.