The invention provides an accuracy-variable magnetic railing ruler based on array nozzle electro-spinning direct writing and a device and method for manufacturing the accuracy-variable magnetic railing ruler. For the accuracy-variable magnetic railing ruler based on array nozzle electro-spinning direct writing, non-magnetism-conducting polymer fibers which are regularly arrayed are firstly and directly written through the array nozzle electro-spinning direct writing technology,and therefore a non-magnetism-conducting thin film is formed to serve as a substrate; then, the polymer fibers which are regularly arrayed and mixed with hard magnetic material particles are directly written, so that a thin film which is of a structure regularly and evenly distributed and is provided with a magnetic surface is formed to serve as a magnetic ruler, magnetic waves are recorded on the magnetic thin film through a magnetism recording head, and therefore the magnetic railing ruler is manufactured. The accuracy of the magnetic railing ruler can be changed when the magnetic railing ruler is installed and measured according to the requirement for the measured accuracy. Due to the fact that the polymer electro-spinning thin film is strong in adsorption performance, the accuracy-variable magnetic railing ruler based on electro-spinning direct writing can be adsorbed to a measured workpiece, can be synchronously expanded or contracted along with the measured workpiece and is strong in adaptability to the change of the environment. According to the array nozzle electro-spinning direct writing technology, a plurality of electro-spinning depositions can be directly written with high accuracy, and the production efficiency is high on the premise that the production accuracy is guaranteed.