Disclosed is a trocar, comprising a trocar sleeve, a sealing structure and obturator, wherein the trocar sleeve comprises a bowl-shaped proximal end housing part, a distal end portion and a sheath portion between the two the sealing structure comprises a top shell and a bottom shell integrated with each other and the obturator comprises a central shaft and a proximal end portion which is located at the proximal end of the obturator designed to be held by a surgeon the axial direction of the trocar is defined by the extension direction of the central shaft which also has an obturator tip at the distal end to perform puncturing the central shaft runs through the sheath portion of the trocar sleeve and the sealing structure in a sealed manner and the obturator tip of the central shaft extends out of the distal end portion of the trocar sleeve when the trocar is assembled. The trocar disclosed by the present invention is characterized in that: the axial dimensions of the proximal end housing portion of the trocar sleeve, the top shell of the sealing structure and the proximal end portion of the obturator in the axial direction of the trocar respectively are d1, d2 and d3, and d3 is equal to or greater than ½ of the sum of d1, d2 and d3. The trocar disclosed by the present invention is advantageous in that when the trocar is in use, the trocar sleeve housing and the sealing structure are unlikely to be separated from each other due to the torque exerted by the surgeon to the joined portion between the trocar sleeve and the sealing structure.
