In this study, the formation of CuInSe2 is based on the Cu/In alloy and selenization processes. First of all, the Cu and In layers is formed by the Bi-layer, Multi-layer and the Co-sputter sputtering processes, respectively. Then annealing process of Cu and In layers is carried out to form the Cu/In alloy, And the CuInSe2 thin film is formed through the selenization heat treatment of this Cu/In alloy. The selenization heat treatment is processed with Se powder inside vacuum quartz tube to form the CuInSe2 absorption layer. Among above three different sputtering processes, the best preparation of Cu/In alloy is carried out through the Co-sputter process with 150°C annealing, and then processed through 550°C selenization leading to the best formation of CuInSe2. This CuInSe2 absorption layer obtained by Co-sputter method under above processes has better performance, its XRD analysis diagram shows that the growth direction of crystal structure in CuInSe2 providing better intensity and less secondary phase of CuxSey and InxSey.