A biopsy rotary cutting device, comprising: an inner cutting cannula and an outer cutting cannula that are coaxially arranged; the inner cutting cannula is located at the inner side of the outer cutting cannula; a piercer is arranged at the head end of the outer cutting cannula; the end of the inner cutting cannula far away from the piercer is directly or indirectly connected with a sample collector; the biopsy rotary cutting device further comprising a dynamic sealing structure that is arranged outside the inner cutting cannula; the dynamic sealing structure forms a cavity outside the inner cutting cannula; the inner cutting cannula comprises a first tube section and a second tube section that are sequentially arranged along the axial direction of the inner cutting cannula; one end of the first tube section is connected with the piercer; the other end of the first tube section is connected with the second tube section; a sealing ring is arranged inside the dynamic sealing structure; the cavity comprises a first cavity located at the side of the sealing ring close to the piercer, as well as a second cavity located at the side of the sealing ring far away from the piercer; the first cavity communicates with an inter-cannula gap that is between the outer wall of the first tube section and the inner wall of the outer cutting cannula; and the end of the inter-cannula gap close to the piercer communicates with the inner side space of the inner cutting cannula; wherein the end of the first tube section close to the piercer is provided with a sharp ended structure; a tube wall portion of the outer cutting cannula close to the piercer is provided with a cutting window; the end of the inner cutting cannula far away from the piercer is directly or indirectly connected with the sample collector; characterized in that the outer diameter of the second tube section is smaller than that of the first tube section and in that when the inner cutting cannula moves to a first position along its axial direction, the sealing ring is located at the outer side of the second tube section, and there is an inter-cavity gap between the sealing ring and the second tube section to enable the first cavity to communicate with the second cavity; and when the inner cutting cannula moves to a second position along its axial direction, the sealing ring is located at the outer side of the first tube section, and the sealing ring is in sealed contact with the first tube section to isolate the first cavity from the second cavity, when the inner cutting cannula moves to the first position along its axial direction, the cutting edge structure is located inside the cutting window; and when the inner cutting cannula moves to the second position along its axial direction, the sharp ended structure is not located at the inner side of the cutting window. the dynamic sealing structure forms a cavity outside the inner cutting cannula; the inner cutting cannula comprises a first tube section and a second tube section that are sequentially arranged along the axial direction of the inner cutting cannula; one end of the first tube section is connected with the piercer; the other end of the first tube section is connected with the second tube section; a sealing ring is arranged inside the dynamic sealing structure; the cavity comprises a first cavity located at the side of the sealing ring close to the piercer, as well as a second cavity located at the side of the sealing ring far away from the piercer; the first cavity communicates with an inter-cannula gap that is between the outer wall of the first tube section and the inner wall of the outer cutting cannula; and the end of the inter-cannula gap close to the piercer communicates with the inner side space of the inner cutting cannula; wherein the end of the first tube section close to the piercer is provided with a sharp ended structure; a tube wall portion of the outer cutting cannula close to the piercer is provided with a cutting window; the end of the inner cutting cannula far away from the piercer is directly or indirectly connected with the sample collector; characterized in that the outer diameter of the second tube section is smaller than that of the first tube section and in that when the inner cutting cannula moves to a first position along its axial direction, the sealing ring is located at the outer side of the second tube section, and there is an inter-cavity gap between the sealing ring and the second tube section to enable the first cavity to communicate with the second cavity; and when the inner cutting cannula moves to a second position along its axial direction, the sealing ring is located at the outer side of the first tube section, and the sealing ring is in sealed contact with the first tube section to isolate the first cavity from the second cavity, when the inner cutting cannula moves to the first position along its axial direction, the cutting edge structure is located inside the cutting window; and when the inner cutting cannula moves to the second position along its axial direction, the sharp ended structure is not located at the inner side of the cutting window.