Provided is a combined cable-girder anchorage structure of the top of a pre-stressed concrete cable-stayed bridge girder. Cable force of a stay cable can be directly transmitted to the center of a web plate so that the transverse eccentric moment on the web plate by the cable force can be eliminated. The combined cable-girder anchorage structure of the top of the pre-stressed concrete cable-stayed bridge girder comprises a box girder and the stay cable (40) with one end anchored to the box girder. A post-poured concrete anchor block (20) is arranged on the top of the web plate (10) at the corresponding position of a girder section of the box girder. Pre-stressed steel beams (30) are pre-buried in the web plate (10) and the post-poured concrete anchor block (20). The pre-stressed steel beams (30) enable the post-poured concrete anchor block (20) to be connected with the web plate (10) to form a stress integrity after being tensioned only at the post-poured concrete anchor block (20) end. A combined anchor bearing plate is pre-buried and fixedly arranged in the post-poured concrete anchor block (20), and one end of the stay cable (40) is anchored to the combined anchor bearing plate.