Theoretical investigation into memorization in a self-memorial model, which is formulated with a truncation equation of finite-amplitude baroclinic wave, is conducted. A corresponding self-memorization equation is derived. An analytical solution of the equation is obtained under conditions of giving memory function as both linear and decay exponential types, meanwhile, the physical meaning and prediction implication of the solution are discussed. It is proved that the zero-order self-memorization equation is irrelevant to a memory function formulation. By calculating a forget factor, some issues on dynamical predictability and retrospective order etc are studied too, and it is pointed out that these issues can be united to a framework of atmospheric memory theory.