Negative pressure ventilation cabinet

The utility model relates to a negative pressure ventilation cabinet which comprises an upper cabinet body and a lower cabinet body, an operation table is arranged between the upper cabinet body and the lower cabinet body, a gas collecting hood is fixedly arranged at the top of the upper cabinet body and communicated with an inner cavity of the upper cabinet body, and a flow guide plate assembly is arranged in the upper cabinet body and comprises a first flow guide plate, a second flow guide plate and a third flow guide plate. A first exhaust gap is formed between the first flow guide plate and the second flow guide plate, a second exhaust gap is formed between the second flow guide plate and the third flow guide plate, and a third exhaust gap is formed between the third flow guide plate and the operation table. Harmful gas in the upper cabinet body is rapidly discharged from the first exhaust gap, the second exhaust gap and the third exhaust gap, the harmful gas is prevented from being gathered in the upper