Multi-color colored fountain pens are made by inserting 3 or more pen cores into the through hole of the pen head mold according to the design requirements and using an injection molding machine to inject plastic resin into a whole. The roll core of the tightly-capped isolation cover is fixed in the barrel with a gasket, the corrected pen tip is embedded in the end of the pen neck of the barrel, the pen core is inserted into the roll core through the through hole on the gasket to absorb ink, and then the cap is sealed Seal with adhesive to prevent color mixing with the barrel, pen core and gasket, and install a color ring on the end of the pen neck. Combining multiple refills in one pen can write different colors separately, and will not cross or mix colors when placed. It is suitable for mechanized mass production and used for painting work and teaching lectures by teachers.