Research results show that thermal barrier coatings (TBC) with vertical cracks are better for working in gas turbines than other structures. These cracks increase the strain tolerance of the coating and reduce the thermal stresses and improve the performance of thermal shock resistance and increase the life of the coating.Two main factors limiting the life of thermal barrier coatings are oxidation of bonding coatings and thermal stresses resulting from miss-match. Erosion and corrosion are also factors contributing to the destruction of these coatings, especially in the presence of high heat and corrosive environments. So far, many efforts have been made to solve these problems by researchers. Research has shown that laser refinement is a promising technique for improving the life of thermal barrier coatings. Laser glazing provides a remelting and subsequent solidification of the surface resulting in a dense top layer with a new microstructure and reduced surface roughness, free from porosity but with the formation of crack networks perpendicular to the surface. Laser melting process produces a flat and dense layer, but because after concentrating the laser beam on a point, cooling is carried out unevenly, a network of cracks is produced on the surface. Segmented cracks are expected to be beneficial for accommodating the oxidation stress and mis-match stress and increasing the resistance to thermal shock. According to studies, abundant reduction in surface roughness improves erosion resistance and reduces the reaction of corrosion of molten salts with top coatings. However, the research was carried out as a melting of a superficial layer and and no research has been done to obtain the optimum melt depth. In this study, laser remelting of yttria stabilized zirconia(YSZ) at different depths of coating was performed to achieve optimal laser melting depth. In this study, laser remelting of yttria stabilized zirconia (YSZ) at different depths of coating was performed to achieve optimal laser melting depth. For this purpose, substrates of Inconel 718 superalloy coupons were first sprayed with a CoNiCrAlY bondcoat by the HVOF process and then with (YSZ) topcoat by air plasma spraying (APS). After that, the plasma sprayed YSZ thermal barrier coatings (TBCs) were treated using a pulsed Nd:YAG laser. The optimal parameters for laser modification were obtained by changing the laser power, scanning speed and nozzle distance from the surface of the piece. To evaluate and obtain parameters and optimum melt depth, microstructural analysis, thermal shock test and oxidation test were performed. In order to characterize and analyze the results, microstructure study by optical microscope and scanning electron microscopy, elemental analysis was performed using energy Dispersive Spectroscopy(EDS) and fuzzy analysis by X-ray diffractometry (XRD). According to the results of the thermal shock test, the coating failure factor is due to the miss-match of the coefficient of thermal expansion of the overlay and the metal parts of the system, which reduces the laser modification of these stresses And improve the initial thermal shock resistance of 2 to 3 times in all of the laser states and improve more than 3 times the C model (remelting to half the thickness of the coating).The results of the microstructure analysis after oxidation test showed that the thickness of the Thermally Grow Oxid (TGO) and the oxygen content in the surface lasered were lower than the spray coating, which increased again with increasing melting depth. Keywords: Gas turbine, thermal barrier coating with crack, Vertical cracks, Thermal shock resistance, Laser remelting