The invention discloses a fixing device for mounting chemical pipelines. The fixing device comprises an operation box, wherein a controller is fixedly arranged at the bottom of the left side of the operation box, sliding rails are fixedly connected to the two sides of an inner cavity of the operation box, a supporting plate is arranged between the two sliding rails, and first sliding blocks are welded to the two sides of the supporting plate. According to the fixing device, the operation box, the controller, the sliding rails, the supporting plate, the first sliding blocks, a supporting rod, amounting plate, a telescopic rod and a sliding grove, a second sliding block, a bearing plate, a forward and reverse motor, a fixing block, a mounting block, a telescopic frame, a spiral tube and a cylinder are arranged to be matched with one another, so that the problem that an existing pipeline fixing device does not have a lifting function is solved, the height of the fixing device can be adjusted in a certain range according to the height of pipeline mounting, so that different fixing devices do not need to be used when pipelines of a certain height are mounted, the mounting cost is saved, and the labor force required by transportation of the fixing device is reduced.