Horizontal well geosteering method and device and horizontal well steering system

The invention provides a horizontal well geosteering method and device and a horizontal well steering system.The method comprises the steps that element analysis results of a plurality of rock samples are obtained, the element analysis results comprise element types and element contents, and the rock samples are obtained by sampling at a plurality of stratums of a coring well section; constructing a positioning model according to an element analysis result; the current element analysis result is input into the positioning model, the current stratum of the horizontal well is obtained, and the current element analysis result is the element analysis result of rock at the current position of the horizontal well; the horizontal well track is adjusted according to the current stratum and the target stratum of the horizontal well. According to the method, the current stratum of the horizontal well is positioned through the positioning model according to the elemental analysis result of the rock at the current positi