The crystal structure of new quaternary R3Al3CuGe2(R=Gd,Tb,Dy,Ho,Er,Y)compounds were studied by Rietveld method from X-ray powder diffraction data.The R3Al3CuGe2 compound crystallized in the hexagonal Er3Al3Ge2Ni-type structure with space group P-62m(No.189).The crystal structure,magnetic moment,and mechanical properties of R3Al3CuGe2 were calculated by first principles calculations based on density functional theory(DFT)with the generalized gradient approximation(GGA).The calculated equilibrium lattice constants are in excellent agreement with experimental results,which imply the reliability of the present calculation method and the results.