The works aims to study the influence of residual oxygen on micro-arc spark deposition. Single pulse, multiple pulses and 2 min deposition were performed in argon-rich shielding atmosphere with different residual oxygen concentrations. The scanning electron microscope (SEM), optical microscope (OM) and hardness tester were used to analyze the characteristics of deposition coating. When the residual oxygen concentration was 0.04%~0.06%, the deposition spots displayed a typical splashy appearance. For 2 min deposition, the irregular morphology deposited coating with a maximum thickness of ~140 μm was obtained. When residual oxygen concentrations were 0.4%~0.6% and 1.4%~1.6% (other parameters were the same), the deposition spots showed flat surfaces without splash on the edge. After 2 min deposition, the novelty column structures with embryos were observed on the substrate. The results of mass transfer trend showed that the mass transfer efficiency was increased with appropriate residual oxygen concentration. The maximum mass transfer coefficient was the highest about 91%, when the oxygen concentration was 0.4%~0.6%. From the hardness test results, the microhardness of coating was 290~330HV, slightly lower than the value of the substrate (~356 HV). Temperature gradient coefficient of the surface tension is dramatically affected by the residual high-active element oxygen in argon-rich shielding atmosphere. The morphology of deposition spot is changed from splash to aggregation with the existence of appropriate residual oxygen, thus resulting in the novelty column structure with embryos.