Abstract: In view of the anchor problem of large-tonnage fiber reinforced polymer (FRP) composites cable, basing on previous proposed integral variable stiffness anchor method suitable for multi root and large-diameter FRP composite cables(large-tonnage anchor for short), the essential reason of stress concentration at the loading end of FRP composite cable was analyzed based on the relationship between stress and strain, and the interfacial friction coefficient relationship of cooperative work between the FRP composites and load transfer component was deduced. Based on the principle of work and power, the calculation formula of anchor force for large-tonnage anchor was derived, and the parameter analysis was carried out based on the calculation formula of anchor force. The theoretical derivation results show that the stress concentration at the loading end of FRP composite cable can be caused by load transfer component with equal stiffness, and the large-tonnage anchor basing on load transfer component with variable stiffness can effectively avoids the cut effect of FRP composite cable. The derived interfacial friction coefficient relationship can be used as the basis for judge whether FRP composite cable and load transfer component follow up synchronously. The parameter analysis shows that increasing the anchor length and the cone angle (keeping the thickness of loading end unchanged) is advantageous to design small size and large-tonnage anchor system, while increasing the cone angle (keeping the thickness of free end unchanged) and the thickness of the loading end and the free end simultaneously is disadvantageous to design small size and large-tonnage anchor system.