A flow guider and a wiper assembly for wiper, wherein a spring rail is detachably received in the flow guider which is provided with a longitudinal slot providing along the extension direction of the flow guider for accommodating the spring rail, and a receiving portion being able to receive the edges of the spring rail is provided on the side portions of the flow guider forming the longitudinal slot, for restricting the breakaway of the spring rail from the flow guider, wherein at least one stopper is provided on the longitudinal side walls of the longitudinal slot of the flow guider, a stop portion is provided on the spring rail for cooperating with the stopper, and the mutual cooperation of the stopper and the stop portion can stop the breakaway of the spring rail from the flow guider in the extension direction of the flow guider.