According to GJB1179A-2012 "Quality Requirements for Low Speed and High Speed Wind Tunnel Flow Fields", the velocity field calibration is a key item in the wind tunnel flow field calibration and an important basis for evaluating whether wind tunnels have the ability to conduct model tests. Center line probe is a universal calibration instrument used for velocity field calibration in the subsonic and transonic wind tunnels. In order to reduce the disturbance of the center line probe on the flow field and generate an undisturbed flow field in the test section, it is generally required that the blockage degree should not exceed 0.5%, and the head cone is located in the contraction section of the wind tunnel. In recent years, with the construction of large-scale transonic wind tunnels of over 2 meters in China, traditional center line probe design schemes face certain difficulties in the manufacturing, installation and calibration. In response to this issue, the aerodynamic shape and installation position of the head of the center line probe is optimized, achieving the weakening of the intensity and disturbance range of the conical shock wave at the head of the probe, and exerting the wave attenuation ability of the acceleration zone in the test section. A non-interference flow field consistent with traditional long center line probe is generated in the test section, greatly shortening the length of the probe. The present study provides a feasible technical solution for the design of center line probe for velocity field calibration in large-scale transonic wind tunnels.