The invention discloses a quick dismantling and installing knife group of a food processor and the food processor thereof. When the knife group needs to be installed, a movable sleeve is pressed downto make a press fit portion of a second groove press a sphere steel ball on a first groove, so the whole knife group is fixed on a motor rotating shaft; when the movable sleeve is pulled upwards to make an accommodating portion of a second groove level with the sphere steel ball, the sphere steel ball falls into the accommodating portion, at the time the sphere steel ball no longer presses the first groove, a middle casing together with the movable sleeve and a stirring knife group can be pulled out directly, to be separated from the motor rotating shaft, and the quick removal of the whole knife group is implemented. The structural design is reasonable and simple, the mounting and dismantling are simple, convenient and fast, and the cleaning of a cup and the knife group is facilitated.