Multi-nozzle 3D printer and printing method

The invention discloses a multi-nozzle 3D printer and a printing method. The multi-nozzle 3D printer comprises a lifting rotary tray, a printing nozzle assembly moving in the direction X and the direction Y and six printing nozzles synchronously stretching out and drawing back in the radial direction of a supporting arm. The printing nozzles and the tray relatively rotate, and the multi-nozzle 3D printer is especially suitable for printing a large. A ball screw drives the rotary tray to move vertically, and product stacking in the height direction is achieved. A fifth driving motor drives a large gear to rotate, six small gears are engaged with the large gear, the small gears do reciprocating motion through a synchronous belt and a sliding block in the radial direction, and all the printing nozzles can be driven to work synchronously; at most six products can be printed at the same time, so that the printing work efficiency of small products is greatly improved; or the six printing nozzles are used for printi