In this research, numerical solution of the system of linear Volterra and Fredholm integral equations are investigated by using improvement of block-pulse functions method. This attempt includes three chapters which are organized as follow. Chapter1is devoted to fundamental concepts of block-pulse functions and improvement of block-pulse functions, expanded functions to its improvement of block-pulse functions series and computation of their operational matrix of integration. In chapter2, improvement of block-pulse functions method is used for obtaining the numerical solution of systems of linear Fredholm integral equations. numerical solution of systems of linear Volterra integral equations by using this method is presented in Chapter3. To demonstrate the effectiveness of our work several numerical examples are presented at the end of each chapter.