In this paper, a total number of 19clusters of CoNi''s alloy ground state and non-ground-state structures were studied with GEAM by using molecular dynamics method combined with simulated annealing algorithms. In this premise, some thermodynamic properties of clusters were studied by warming up the system. Through this study we found that the ground state structure of the alloy is double icosahedral structure, regardless of the proportion of the alloy, and the ground state energy increases with the rising of the number of Co atoms. In the mean time we studied the alloy clusters'' phase-change properties and found that pure metal and alloy both have pre-melting phenomenon, and the melting temperatures tend to drop with the increasing of Ni atom number when the alloy melts.