Currently,homojunction structure is the conventional structure of the rmo-photovoltaic (TPV) cells,but the heterojunction structure has rarely been investigated.This paper proposes the heterojunntion structure of TPV based on Ge substrates.The GaInP_2and GaAs materials are epitaxied by ment al organic chemical vapor deposition (MOCVD) process.The structural,optical,and electrical properties of GaInP₂/Ge heterojunction material are studied by the methods of (SEM)、X-ray diffraction (XRD),EVC,photo lyminescence (PL).We obtain single c rystalline materials GaInP_2with wide band gap,high photo-absorption coeffici ent and perfect lattice matching with Ge substrate.It will contribute to high ef ficiency thermo-photovoltaic cells.