The purpose of this study is to develop a method of calculating the vibration partition function of diatomic molecules for the Morse potential energy. After a brief introduction about the eigensolutions obtained for the problem in question, Via the Euler-Maclaurin formula, we have determined the thermal properties for four diatomics such as \text{H}_{2}, HCl, LiH, and CO. Different situation has been exposed and explained by the appropriate curves of the thermal properties for these diatomics molecules in consideration. In addition, we have shown that our method exposed to calculate these thermal properties can be used to determine these thermodynamic quantities.