The invention provides an installation method of resettable two-grade deviation switches of a belt conveyor. The installation method is characterized by comprising the following steps: (a) arranging the two-grade deviation switches at the head part, the tail part, a convex arm section and a concave arc section of the belt conveyor or the middle position of the belt conveyor and arranging the double-stage deviation switches in pairs at the two sides of the belt conveyor; (b) preferably setting the distance from an upright roller of each deviation switch to a normal position of a conveying beltto be 50-100 mm; (c) setting two grades of angle for the two-grade deviation switches; and (d) additionally installing one reset button in a regular control circuit of each pair of two-grade deviationswitches, making a binding post (a) of each reset button be connected with an output end of a start button in series, and making a binding post (b) of each reset button be connected to an input end of a weight deviation signal control circuit in series. The installation method provided by the invention has the advantages that each two-grade deviation switch of the belt conveyor is simple in structure and convenient to manufacture; the problem that the belt conveyor cannot be started if the two-grade deviation switches are not reset when the belt conveyor stops working due to weight deviationcaused by uneven load of a belt or ultrahigh length of the belt is solved; and conditions are created for belt deviation correction work.