The invention discloses a negative-pressure filtering device. The negative-pressure filtering device comprises a negative-pressure bottle, a vacuum pump connected with the negative-pressure bottle and a funnel arranged on the negative-pressure bottle, wherein a rubber plug is arranged at the connection part of the funnel and the negative-pressure bottle; a pressure regulating cavity is arranged at the upper end of a side wall of the negative-pressure bottle; the pressure regulating cavity is provided with a gas inlet channel and a pressure regulating channel connected with the vacuum pump; a ventilation channel is arranged between the pressure regulating cavity and the lower end of the side wall of the negative-pressure bottle; a control valve body is arranged in the ventilation channel; a control knob connected with the control valve body is arranged at the outer part of the negative-pressure bottle; a flow regulating valve is arranged on the pressure regulating channel. The negative-pressure filtering device is simple in structure and convenient to operate; the connection or disconnection of the pressure regulating cavity and the negative-pressure bottle can be effectively controlled according to requirements, so that gas pressure in the funnel is approximate to gas pressure in the negative-pressure bottle, and the funnel and the negative-pressure bottle can be conveniently and easily separated, and furthermore, the working efficiency can be improved to a certain extent; the negative-pressure filtering device is good in utilization stability, strong in adaptability and good in practicability.