The invention discloses concentric double-pipe gas injection and heat insulation analyzing method and device for a horizontal well. The method comprises the steps of acquiring well body structure and thermophysiciaity parameters, wellbore injection parameters and strata thermal property parameters; determining the thermal resistance of a well body structure; further determining the maximum heat loss at a wellbore, the strata mean temperature per unit length, heat loss speed per unit length from a heat insulation pipe to the well wall, heat loss speed per unit length of an inner pipe, steam dryness of annular spaces in the heat insulation pipe and the inner pipe, and steam dryness of the inner pipe, so as to determine the thermal-convection resistance in the annular spaces; correcting the heat loss speed per unit length from the heat insulation pipe to the well wall according to the thermal-convection resistance in the annular spaces; iteratively analyzing the corrected heat loss speed per unit length from the heat insulation pipe to the well wall to generate a concentric double-pipe gas injection and heat insulation analyzing result for the horizontal well. According to the scheme, the method and device are high in calculation stability and relatively high in calculation precision, can predicate and adjust the concentric double-pipe gas injection process parameters of the horizontal well, and are of practical signification on improving the yield of heavy oil horizontal well in an oilfield.