The invention provides a spread foundation structure shaped like a Chinese character 'pin', and aims at better meeting the stress requirement of a bridge span structure, reducing foundation displacement, improving the structural-load-carrying capacity and reducing the constructional difficulties and construction risks. The spread foundation structure comprises a pier stud, a spread foundation and bed rock, the spread foundation is located on the bed rock, and the pier stud is fixedly solidified to the upper portion of the spread foundation. The spread foundation is formed by arranging a foundation upper part and a foundation lower part in an up-and-down stacked mode, the foundation lower part is arranged on the bed rock and tightly attached to the bed rock, and the foundation upper part is connected with the pier stud; the width of the foundation upper part in the transverse direction of a bridge is smaller than that of the foundation lower part in the transverse direction of the bridge.