The invention relates to an internal-cooling 
microwave ablation needle provided with an implanted 
balloon. A 
microwave antenna is insulated from an internal cooling 
system through a 
microwave antenna liner tube, the internal cooling 
system is in positioning connection with an outer tube through an adapter tube and a sealing tube, and the 
balloon is located between a targeted area and a non-targeted area of the 
microwave ablation needle and connected with a J-T spray tube through the adapter tube; the J-T spray tube is connected with a finned tube, the 
balloon is filled with fluid through the adapter tube, the balloon after filling of the 
cooling fluid is expanded and has a fastening effect with surrounding tissue; when low-temperature gas is introduced, small frozen areas are produced around the balloon under the action of the throttling effect of the J-T spray tube, and the fixing function is realized; a vacuum wall is arranged on the inner side of the outer tube, so that the fluid in the outer tube is in heat insulation from 
biological tissue outside the outer tube, and 
normal tissue is protected from cold injuries. The internal-cooling 
microwave ablation needle can be effectively prevented from displacement with shrinking deformation of heated 
biological tissue in an 
ablation process, and has the advantages that an 
ablation area is positioned more accurately, fewer 
normal tissue injuries are caused, the risk of the 
needle track implantation of tumors is lower and the like.