The invention provides a split-type disease and insect pest pesticide liquid spraying device based on corn planting. The split-type disease and insect pest pesticide liquid spraying device comprises aleft bearing, a right bearing, a driving wheel and a pull frame; a left frame and a right frame are both L-shaped plate bending pieces, and the inner end faces of the left frame and the right frame are jointly connected with a function bin; the left bearing and the right bearing are symmetrically installed on the top faces of the left frame and the right frame left and right, and mobile wheels are further installed on the bottom faces of the left frame and the right frame through welded wheel frames; a welding plate is vertically welded to the left side of the top face of the left frame, a semi-circular arc opening is formed in the top of the welding plate, and a lateral leather bag is in screw fixation with the semi-circular arc opening. Other complicated mechanisms actuated by a fertilizer application mechanism are omitted, and a helpful structure with two kinds of functional linkage actuation is achieved. In this way, the split-type disease and insect pest pesticide liquid sprayingdevice is simple in structure and can complete fertilizer application and downward pesticide liquid spraying simultaneously after being hung on an agricultural vehicle, and therefore, agricultural bacteria which are turned out when soil is turned in the last working procedure are quickly killed in the next working procedure of fertilizer application.