Abstract: A concept of thin-walled and thick-walled parts was proposed for plasma-spraying coating parts, and a mathematical model based on superposition principle established to calculate residual stresses. The results showed that both tensile stress and compressive stress may arise in the coating. The limit value of residual stress appears in the combination zone of substrate and coating. The relaxation of residual stress was effectively estimated with layer model and stress superposition method. The experimental results agree with the calculated results. The effect of thermal expansion coefficient, preheating temperature of substrate and coating thickness on residual stress is great. These results may provide a valuable reference for the design of plasma spraying coating.