The design of ventilation and dust control system has become the important part of environmental projects to provide a safe and health working condition for workers. A computer aided design software was developed based on ventilation and dust control theory using Visual Basic to help engineers to design ventilation system efficiently and conveniently. The software developed could help users to determine air flow rate, velocity, diameter of ducts, resistance of the system, fan, duct collector based on database of the software. The design project could be finished quickly following the design process in computer aided ventilation and dust control software which is effective and practicable.