The invention relates to a space printing nozzle applied to a mechanical arm. The space printing nozzle is composed of a mechanical part and an electronic control part, wherein the mechanical part comprises a flange plate, an acrylic base plate, a stepping motor, a nozzle latch, a central rotary plate, a fixed D printing nozzle, a movable D printing nozzle, a cold air pipe and a KUKA six-shaft mechanical arm; the stepping motor is connected with a gear set; the nozzle latch is fixed on the acrylic base plate; the movable D printing nozzle is positioned at the periphery of the fixed D printing nozzle, one end of the movable D printing nozzle passes through the nozzle latch, and the end part of the movable D printing nozzle is connected with a material inlet pipe; one end of the fixed D printing nozzle passes through the central rotary plate to be fixed on the acrylic base plate, and the end part of the fixed D printing nozzle is connected with a material inlet pipe which is connected with a material extruder; the central rotary plate is connected with the gear set; the cold air pipe is arranged beside the printing nozzle; the electronic control part is composed of five stepping motor control panels, a control panel expansion board, a main control plate, an operation panel, a bread board, an LED display screen and an LED display screen control panel. The space printing nozzle is simple in structure and convenient to operate.