The invention provides a monitoring system and a monitoring method for an EGR one-way valve. The monitoring system comprises a differential pressure sensor, a controller electrically connected with the differential pressure sensor and a Venturi tube connected in a waste gas recycling loop. A first pressure measuring channel (144) and a second pressure measuring channel (145) are formed in the outer surface of a throat part of the Venturi tube. The first pressure measuring channel (144) communicates with an inlet section (141) of the Venturi tube along a straight line, the second pressure measuring channel (145) firstly extends in the direction perpendicular to the axis direction of the Venturi tube, then turns to the direction of an outlet of the Venturi tube at the position close to the inner surface of a throat and finally communicates with a transition part of a throat section (142) and a diffusion section (143) of the Venturi tube. Channel openings, formed in the outer surface of the throat part, of the first pressure measuring channel (144) and the second pressure measuring channel (145) are taken as two pressure measuring points of the differential pressure sensor. By means of the monitoring system, the state of the one-way valve can be effectively monitored, and damage caused by the damaged one-way valve to an engine is avoided.