The invention discloses a method and a device for measuring an HgCdTe Te-rich liquid phase epitaxy Au in-situ doped segregation coefficient. The method disclosed by the invention comprises the following steps: assuming a segregation coefficient firstly to obtain the content of Au in a unit volume of Au-HgCdTe mother solution, calculating the contents of Au, Hg, Cd and Te in the Au-HgCdTe mother solution, then carrying out mother solution synthesis and liquid phase epitaxy, finally removing a substrate to obtain a pure Au-HgCdTe film, then testing an actual doping concentration of Au in the Au-HgCdTe film with an ICP-OES (Inductively Coupled Plasma Optical Emission Spectroscopy), and finally calculating the HgCdTe Te-rich liquid phase epitaxy Au in-situ doped segregation coefficient according to a formula of the segregation coefficient and in combination with the content of Au in a unit volume of Au-HgCdTe mother solution. According to the method and the device disclosed by the invention, the problem that the prior art cannot be applied to measurement of the HgCdTe Te-rich rheotaxial Au in-situ doped segregation coefficient is solved, and testing results with high accuracy can be obtained.