Abstarct: The buckling and vibration responses of nanoplates made of functionally graded materials (FGMs) subjected to Thermomechanical loading under four types of thermal loads are studied in prebuckling domain with considering The effect of surface stress. Types of thermal loads is, Linear Temperature Distribution and Nonlinear Temperature Distribution. Mechanical load is constant. To accomplish this purpose, Gurtin–Murdoch elasticity theory is incorporated in to the classical plate theory to develop a non-classical plate model including the surface effects. The material properties of FGM nanoplate are considered to be gradedin the thickness direction on the basis of the power law function. Hamilton's principle is utilized to derive size-dependent governing differential equations of motion and associated boundary conditions. Selected numerical results are presented to indicate the importance of surface stress effect. It is revealed that in the presence of surface stress effect, the influence of material property gradient index on the critical thermal buckling load is more prominent for FGM nanoplates with lower length-to-thicknessr atios. Also, by increasing the natural frequency of FGM nanoplate, the role of surface stress effect in the value of critical thermal buckling load is more prominent.