The current study focused on design and analysis of a modular CanSat rocket intended to reduce the cost of the modular rocket, which is reusable and carry a payload consists of two CanSats, and it is powered by a solid propellant rocket motor, which is a commercial type to reduce the total cost and complexity. The majority of the emphasis was placed on the design of the motor case and the separation mechanism. This work was done as a proof of concept that separation mechanism can be based on a mechanical system, which detects rocket apogee using magnetometer. Moreover, the motor case and body type of the rocket designed to fit two different dimensions of a motor diameter, which provides different maximum altitude. The study being with the mission design requirements are given to be consistent with standard dimensions of the CanSat. Then, a background about the commercially available modular rocket in the market. Then, a review study for the rocket dynamics and aerodynamics of flying conditions is introduced.