The invention aims to provide a fertilizer fixed-point adding device as well as a fertilizer and a seed fixed-point adding device and a method. The fertilizer fixed-point adding device comprises a shell, a feeding opening, a discharging opening, an input pipe and an output pipe, wherein the feeding opening and the discharging opening are formed in the upper part and the lower part of the shell respectively; the feeding opening is communicated with the input pipe; the discharging opening is communicated with the output pipe; the shell is cylindrical and is internally provided with a material scraping valve plate and a valve plate shaft; the valve plate shaft is arranged at the circle center of the shell and the axial direction of the valve plate shaft is parallel to that of the shell; the material scraping valve plate is fixedly mounted on the valve plate shaft and can rotate around the valve plate shaft; the shape and the size of the material scraping valve plate are matched with the central section of the shell to divide the inner space of the shell into two parts. The invention further provides the fertilizer and seed fixed-point adding device adopting the fertilizer fixed-point adding device and a seeding and fertilizing method of the fertilizer and seed fixed-point adding device. According to the fertilizer fixed-point adding device as well as the fertilizer and seed fixed-point adding device and the seeding and fertilizing method, the problems that an existing fertilizer adding device ablates buds and fertilizers are wasted are solved.