We use the block pulse functions (BPFs) and their operational matrix to approximate solution of a system of multi-term fractional mixed Volterra-Fredholm integro-differential equations. Firstly, we homogenize it and then convert it to the system of algebraic equations. By solving the system of algebraic equations, a numerical solution is obtained.After demonstrating the method's convergence, several examples are presented. Comparing the results confirms the proposed method's applicability, accuracy, and efficiency.