To have a high quality experimental growth of crystals,understanding the equilibrium crystal shape (ECS) in different thermodynamic growth conditions is important.The factor goving the ECS is usually the absolute surface formation energies for surfaces (or edges in 2D) in different orientations.Therefore,it is necessary to obtain an accurate value of these energies in order to give a good explanation for the observation in growth experiment.Historically,there have been different approaches proposed to solve this problem.This paper is going to review these representative literatures and discuss the pitfalls and advantages of different methods.