The efficient control of buoyancy with low power is critically important in the design of new age 'Autonomous Underwater Vehicles/Gliders (AUVs/Gs)'. This paper presents a 'Computer Simulation Model (CSM)' for the primary design of 'Variable Buoyancy System (VBS)' for AUVs/AUGs to efficient control buoyancy and the simulation model is built in the environment of integration, modular architecture and specific range of applicability. The CSM for design of VBS is integrated in the overall design process of AUVs/AUGs. Finally, we present design example of the VBS for a AUVhaving two ballast tanks (each of a buoyancy capacity of ± B = 10kg), maximum rate of change of buoyancy = 9 kg/minute; and our presented results show that the proposed CSM for the design of VBS for AUVs/AUGs simulates the design process efficiently and leads to an efficient and economic design with the desired and specific range of applications. © 2016 IEEE.