Enaminones are chemical compounds consisting of an amino group (−N=) linked through a C=C to a C=O group. In this research, four various enaminone structures were theoretically optimized. These enaminone structures have been studied for substituent effect on hydrogen bond, method and basic set effects on the geometrical parameters, vibrational frequencies and etc. Drawing molecular structures and computer calculations were performed with Gauss view (5.0) and Gaussian (09) softwares, respectively. The utilized methods in the paper were the HF and DFT and of DFT methods of basic functions B3LYP and B3P86. Also Basis sets of 6-311G, 6-311G*, 6-311G**, 6-311+G** and 6-311++G** have been utilized. Generally the results of computer calculations and comparing them with experimental equivalents indicate that theoretical procedures could well be helpful and effective in enaminone studies and offer reasonable and well results. Enaminone structure was studied for tautomerism and it was revealed that Ketamine form is more stable than Enolimine form.