The work aims to optimize the microstructure and performance of IN939 nickel-based superalloy coating. Coaxial powder feeding laser system was used to prepare IN939 coatings and the coatings were divided into four groups: one group was used as the control group and the other three groups respectively underwent solution treatment, aging treatment and complete heat treatment (solution + aging). The microstructure and phase composition were analyzed by optical microscope (OM), scanning electron microscope (SEM) and X-ray diffraction (XRD). The effects of heat treatment on hardness and corrosion resistance of the coatings were studied by microhardness test and electrochemical corrosion test. Laser cladded IN939 superalloy coatings had good morphology, without defects such as pores and cracks. Before heat treatment, γ′ precipitation was hardly found in the coating, but γ′ precipitation appeared in the three groups of coatings after heat treatment. Furthermore, the average size of γ′ particles precipitated after solution treatment was about 60 nm, while that after aging treatment and complete heat treatment was about 100 nm. In addition, the hardness of the coating was improved after the heat treatments. The average hardness of the coating after aging treatment was 472.7HV0.2, which was 10.2% higher than that before heat treatment. The average hardness of the coating after complete heat treatment was 475.6HV0.2, which was 10.9% higher than that before heat treatment. The electrochemical corrosion test results showed that the current density values of the IN939 coating after single aging treatment and complete heat treatment were much smaller (3.014×10-7 A/cm2, 3.441×10-7 A/cm2, respectively) and the polarization resistance of the coating was increased by 35.1% and 39.3%, respectively, greatly reducing the corrosion rate. Heat treatment can precipitate γ′ phase in laser cladded IN939 coating, and the size and distribution of γ′ particles precipitated via aging treatment and complete heat treatment are basically the same. Additionally, heat treatment can improve the hardness and corrosion resistance of the coating. The complete heat treatment has the most obvious improvement on the performance of the coating, followed by single aging treatment.