A new tumor cryoablation catheter comprises a balloon (1) and pipelines connected with a proximal end of the balloon (1), and the pipelines are covered with a heat insulation layer. The pipelines comprise a gas intake pipeline (2) and a gas return pipeline (3), and a distal end of the gas intake pipeline (2) extends into the balloon (1). The balloon (1) comprises a distal surface (11) at a distal end. During ablation, refrigerant input from the gas intake pipeline (2) expands the balloon (1), and the distal surface (11) is spread to form a flat surface at the distal end of the balloon (1). A proximal portion (12) of the balloon (1) bulges to form a hemispherical shape, and the refrigerant flows back through the gas return pipeline (3). The gas intake pipeline (2) extends into the balloon (1), to ensure a full release of the refrigerant, improve heat exchange of the refrigerant, and enhance effect of cryotherapy. When the balloon (1) is spread, the distal end of the balloon (1) has minimal deformation, thus ensuring the distal surface of the balloon (1) to be a flat surface, accordingly avoiding a point contact between the cryoablation catheter and tissues of human body, increasing the freezing area, and providing a better effect for application to a large-sized tumor.
