The objectives of this book is to present the fundamentals of Solid Rocket Motor, starting from the elementary analysis of rockret propulsion and then justifying the need of sophisticated computation of the internal flow. After a brief reminder of solid rocket theory, a description of its main components is proposed. The elementary parameters controlling the operation are introduced and the basic formula predicting the steadystate operation pressure is established. In this book, we have described about solid solid rocket propulsion and we explored some of the issues which are related to the performance of the whole rocket. We have also described the main design of the rocket engine and its performance related factors and design aspects which affect the perfomance of the motor, and practical limitations for motor design. The main issues faced by the Solid Rocket Engine require an accurate description of internal aerodynamics, either to predict the pressure/thrust programs and the normal transient phase like ignition, or to motor stability. A short overview of the evolution of the Solid Rocket Motor internal aerodynamics during the last thirty years is also given in the book. It is hoped that this book will provide an introductory substance to the field of solid rocket propulsion.