Abstract: For problem of gas overrun in switchover of mine main ventilators, the paper analyzed existing switchover scheme of main ventilators, and indicated that key problem of switchover of main ventilators without off-blast is avoiding the running ventilator and the standby one running in rated condition simultaneously in switchover process. It proposed a switchover scheme of mine main ventilators without off-blast, which could be implemented in an automatic control way with PLC technology. Finally, It analyzed requirements on power supply system and main questions in implement of the scheme and considered that the system has strong feasibility.