With drill pipe steel S135 as the research object, this paper aims to study the effect of spraying power on the structure and properties of the coating by plasma spraying of Al2O3-TiO2 coating on the steel substrate on the basis of not destroying the excellent mechanical properties of S135 steel. Al2O3 + TiO2 coatings were prepared on the surface of S135 drill pipe material under three spraying powers of 25 kW, 30 kW and 42 kW respectively. SEM morphology observation and XRD phase analysis of three coatings were carried out. The metallographic structure of the cross-section was observed and the micro-hardness at different positions was measured. The bonding strength between coating and matrix was measured with a material surface performance tester. Microstructure, morphology and properties of sprayed coatings at different spraying powers were compared. The results showed that under the three power conditions, the coating consisted of α-Al2O3, γ-Al2O3, Al2TiO5 and TiO2. With the increase of spraying power, the content of γ-Al2O3 and Al2Ti5 in the coating increased, and defects such as pores and cracks in the bonding layer decreased. The bonding strength between the coating and the substrate reached 92 N at 42 kW spraying power. The grain refinement occurred to S135 matrix near the spraying interface during the spraying process due to normalization. Under three power conditions, the hardness of the coating surface was much higher than that of the bonding layer and the matrix. The surface hardness of the coating reached 1419.6 HV when the spraying power was 30 kW. By changing the spraying power, Al2O3-TiO2 coating with high hardness and high bonding strength with the substrate can be obtained on S135 drill pipe material.