The invention provides a design method of the pre-arch shape of the prestress tube bundle or tube panel of a photothermal heat absorber and belongs to the technical field of prestress design. The method includes: solving a temperature field, solving a tube bundle or tube panel deformation shape, solving normal-temperature stress oP when energy input is not considered, determining a regulating coefficient k, and determining the arch curve of the tube bundle or tube panel. The method has the advantages that the bending pre-arch shape of the tube buddle or tube panel of the photothermal heat absorber can be fast and accurately designed by the method; prestress is applied to the tube buddle or tube panel of the photothermal heat absorber according to the pre-arch shape curve calculated by themethod, the capacity, for bearing maximum thermal flux density, of the tube buddle or tube panel of the photothermal heat absorber can be increased effectively, and accordingly the tube buddle or tubepanel of the photothermal heat absorber can satisfy normal-temperature strength requirements and the strength requirements of the heat absorber under actual working temperature during Illumination.