The invention discloses a self-powder-taking 3D printer powder paving system, and belongs to the field of added material manufacturing. The system uses a powder paving motion of a multifunctional powder paving box for skillfully taking powder to realize automatic two-way tool change and powder pavement; after the powder paving box retreats to contact with a slide plate, the powder paving box can push the slide plate to retreat until a powder outlet of a powder supply box is opened; after the powder outlet of the powder supply box is opened, powder to be used is leaked into the powder paving box from an abdominal cavity of the powder supply box until the powder paving box is full; when the powder paving box is returned, the slide plate closes the powder outlet of the powder supply box under the effect of a spring; when the powder paving box advances, the powder to be used in the powder paving box is leaked out from a powder outlet at the lower end of the powder paving box, and is flatly paved on a forming cylinder through a scraper at the lower part; and the system is unique in structure, low in cost and high in efficiency.