The invention discloses an anti-wire-drawing 3D printing pen with adjustable diameter. The anti-wire-drawing 3D printing pen with adjustable diameter comprises a material guiding pipe, a hot melt chamber, a pen holder, throat pipes and a pen head. The hot melt chamber is formed in the bottom end of the interior of the pen holder, the material guiding pipe is disposed in the pen holder, the top endof the material guiding pipe extends to the top of the pen holder, the bottom end of the material guiding pipe is in communication with the hot melt chamber, and a heating pipe is arrange in the penholder of the outer side of the end, close to the hot melt chamber, of the material guiding pipe. The throat pipes are evenly spaced between the pen head and the pen holder, so that the surface area of the throat pipes can be utilized to increase the heat dissipation area of materials conveniently without affecting material circulation, and air can circulate between adjacent throat pipes, so thatthe printing pen is driven to move in the process of combining with the use of the printing pen; and the flow of the air between the throat pipes is further increased, the heat dissipation effect is improved, the solidification efficiency of the materials is improved, and the situation that the materials are excessively soft to affect the effect of printing in the process of printing is avoided.