The utility model relates to an improved cooling water pump for an internal-combustion engine, in particular to a flow guide type cooling water pump with a circular arc surface structure cavity. The flow guide type cooling water pump is provided with a pump shell; a pump shaft is installed at the position of a bearing of the pump shell by the bearing; a transmission belt pulley, a water seal and an impeller are respectively installed on the pump shaft; an end cover is also installed at the right side of the pump shell; a water outlet is arranged in the end cover; particularly, the shape of a corner on the inner wall of an inner cavity of the pump shell is of a circular arc surface structure; a flow guide cone is installed at the water outlet of the inner cavity of the pump shell; and a flow guide cover is installed at the right side of the inner cavity of the pump shell positioned at the water seal. Through the flow guide type cooling water pump, the problems of large noise, low work efficiency and short water seal impact, abrasion and service life of the existing cooling water pump for the internal-combustion engine are solved. The utility model is mainly used for the improvement of the existing cooling water pump for the internal-combustion engine.