The correlation between particle in-flight parameter,defect content and mechanical property of yttria-stabilized zirconia coating was systematically studied in the present work.The melting state of in-flight particle during spraying was simulated using computational fluid dynamics.The results suggested that,with the increase of velocity and temperature of in-flight particles in the plasma jet,the particles changed from partially melted state to fully melted one.As a result,the total defect content of as-sprayed coating gradually decreased,while elastic modulus and microhardness increased correspondingly.However,the fracture toughness of as-sprayed coating reached a maximum value when the total defect content reached approximately 9.1％.