The formation of copper nanowires inside a carbon nanotube (CuNW@CNT) and boron-nitride nanotube (CuNW@BNNT) and the compressing behavior of the resulting composite structure were studied using molecular dynamics. After optimizing C(5,5) and BN(5,5) nanotubes filled with copper atoms, coaxial CuNW with an axial monatomic chain is formed inside the C(5,5) and BN(5,5). Analysis of the radial distribution function on the CuNWs shows that the CuNW inside CNT has better one-dimensional uniform distribution, whose crystallinity is better. And the CuNW inside BNNT has larger atomic distribution density, which can effectively enhance electrical conductivity for one-dimensional nanowire. Comparison of the axial compressing behavior of CuNW@C(5,5), CuNW@BN(5,5), C(5,5) and BN(5,5) reveals that the critical buckling strains and the total potential energy loss of CuNW@C(5,5) composite structure are bigger than that of CuNW@BN(5,5). The results indicate that the compressive resistance of CuNW@C(5,5) is stronger, but the protective effect on CuNWs at buckling is inferior to that of CuNW@BN(5,5).