The utility model relates to a connecting device of an offshore pile foundation structure. The connecting device comprises a load-bearing blind plate, a guide port, a positioning ring and a reinforcing rib plate, wherein the lower part of the load-bearing blind plate is connected with the pile foundation structure, and the upper part of the load-bearing blind plate is sequentially provided with the positioning ring and the guide port; the external parts of the positioning ring and the guide port are provided with upper blocking upright columns and connected with the load-bearing blind plate to form a whole body; and the reinforcing rib plate is arranged in the guide port. The connecting device disclosed by the utility model can be used for building the upper blocking upright columns and the pile foundation structure according to the control accuracy of the general and conventional pile foundation structure without specific control, thereby reducing the offshore construction difficulty and the installation failure risk and increasing the construction efficiency.