Abstarct: One of the relatively simple physical processes that can be successfully described in the introductory quantum theory is the alpha decay which an important decay mode for heavy. It provides us with invaluable knowledge on the nuclear structure, spin- parity, ground state energy, ground state half- lif, shell efect and nuclear intractions. In the present work, we have derived alpha decay by using the quantum theory and WKB aproximation. Then we have focused on the potential which is considered as a barrier. We have explained alpha decay in two chapters: For spherical nuclears, we have calculated half- lives of variouse isotopes by minimalization method, universal approximation method, Yukawa approximation method and by using modified potential. For Deformation nuclears, we have calculated half- lives by universal approximation and Yukawa approximation.