The law of conservation of energy is due to homogeneity of time The energy concept plays a central role in theoretical physics. The law of conservation of energy is a consequence of the homogeneity of time. In this sense, the energy concept is associated with the fundamental structure of the spacetime. The aim of the present thesis is to calculate the energy and momentum of an isolated system in the tetrad theory of gravitation constructed on the spacetime with absolute parallelism (AP-space). In chapter 1 Einstein's trial to construct an energy-momentum complex and the problems that arise from this trial are discussed. M\o ller's discussion to overcome this problem within the framework of the Riemannian space is given. M\o ller's suggestion for the energy-momentum complex using the AP-space is discussed, and also various studies along this direction are given. In chapter 2 a brief review of the AP-space is given. The most general gravitational Lagrangian based on the AP-space, which contains four unknown dimensionless parameters $a_1$, $a_2$, $a_3$ and $a_4$, is discussed. The field equation are derived and the condition which ensures the correct Newtonian limit is given.