The invention relates to a preparation method of a chip of a flip chip type multijunction compound solar cell chip. The method comprises the following steps: adopting vapor phase epitaxy method to prepare the flip chip type multijunction compound solar cell, evaporating the surface of a transferring substrate to prepare a metal electrode with high reflectivity, coating a fenstral phosphor layer onthe surface of the transferring substrate, preparing a fenstral thick metal electrode used for bonding on the surface of the transferring substrate and the surface of the bottom cell of the multijunction compound solar cell, bonding the transferring substrate and the bottom cell of the multijunction compound solar cell, contacting the surface of the phosphor layer with the surface of the bottom cell of the multijunction compound solar cell tightly and removing the epitaxial slice substrate. In the preparation method of the chip, phosphor powder is evenly coated on the surface of the bottom cell of the flip chip type solar cell and the coated phosphor powder can transfer partial solar spectrum with the wavelength of more than 1.2 microns to shorter-wavelength spectrum which has higher spectral sensitivity of the solar cell so as to widen the range of the solar spectrum absorbed by the solar cell and greatly increase the photoelectric conversion efficiency of the solar cell.