Abstract: The present invention relates to a high-speed 3D printer with fused deposition modeling under a closed-loop control and a closed-loop control method thereof, and belongs to the technical field of 3D printing. Since the 3D printer has the grating module in which the grating scale is fixed on the machine frame and the grating reader moves along with the running mechanism, a precise mechanical displacement information of the extrusion spray head can be obtained. For the cross printing running mechanism, a precise movement compensation is realized through the compensation of the closed-loop control to improve the accuracy of the position of the extrusion spray head, and thus greatly improve the accuracy of 3D printing to be able to meet the technical requirements of high-accuracy printing.