The invention relates to an anti-overflow non-flameout device which can solve the problems that petroleum in an oil-gas separator adopting a heating furnace to provide natural gas is excessive and overflows from a top natural gas pipeline, the natural gas pipeline is blocked by the petroleum and heating of crude oil is affected. The scheme is as follows: the anti-overflow non-flameout device comprises a truncated cone-shaped sleeve which is arranged in the positive direction in a gas outlet at the top end of the oil-gas separator, the outer edge of a small circular surface at the top end of the sleeve is hermetically connected with the inner edge surface of the gas outlet, a gap exists between the outer edge of a large circular surface at the lower end of the sleeve and the inner edge surface of the gas outlet, a blocking piece extending into the truncated cone-shaped sleeve is fixedly arranged on the circumference on the lower end surface of the sleeve, an isolation plate is arranged in the sleeve, the lower end of the isolation plate is connected with a floating ball arranged below the sleeve through a connecting rod, and a plurality of ventilation circular holes are uniformly distributed on the circumference at the top of the side surface of the sleeve. The anti-overflow non-flameout device provided by the invention can prevent a large amount of petroleum from overflowing into other devices from the natural gas pipeline at the upper part of the truncated cone-shaped sleeve, and can ensure that natural gas enters the pipeline from the circular holes at the top of the truncated cone-shaped sleeve so as to ensure the normal operation of production.