Abstract: Based on the Embedded-Atom Method, we have performed a semiempirical calculation of structure and cohesive energy for some icosahedra and fcc cuboctahedra copper clusters with atomic number from 13 to 201. The dependence of the cohesive energy on the atomic number and the structure has been elucidated, and a critical size of a crossover from icosahedral to crystalline symmetry has been estimated as n～10³. The results are consistent with available experimental resules.