The correlation between grain morphologies and magnetic properties of CoCrPt/Cr thin films was investigated by varying the sputtering deposition parameters of CoCrPt thin films. Independent of sputtering conditions, the Cr underlayer enhanced Go-grain isolation and limited grain growth in CoCrPt films, resulting in increased coercivity. Cross-sectional transmission electron microscopy indicated a strong separation of the Co grains with increasing argon sputtering pressure, due to the enhanced scattering of argon ions by sputtering particles, and thus the observed higher content of Pt in the deposited films. The Co grains separated by 10-20 Angstrom thick non-magnetic boundaries were found to grow on a single larger Cr grain, resulting in reduced exchange coupling and increased coercivity. The application of substrate bias increased the (101 ($) over bar 0) texture of the Co grains and decreased the grain size of the CoCrPt thin films. Tn addition, the quality of Co epitaxial growth on the Cr underlayer was enhanced by increasing bias, and the boundary,layer between the Cr and CoCrPt films became less distinct as a result of interdiffusion. The magnetic field required to saturate the film increased significantly with increasing substrate bias, possibly due to the induced residual stress in the bias-sputtered films.