Granular CoCrPt-SiO2 thin films with Cr underlayers have been fabricated by sputtering followed by post-deposition annealing. Microstructural and magnetic properties of as-deposited and annealed films have been investigated for potential applications in magnetic recording media. The grain size of about 10 nm was obtained in the as-deposited films, and subsequent annealing did not lead to significant grain growth. High coercivity up to 5640 Oe was achieved upon annealing. The Mrt value can be down to about 0.4 memu cm-2 for films with Hc exceeding 5000 Oe. The peak value of the delta M curves changed from a positive value in as-deposited films to a negative value for annealed films, indicating an obvious reduction of intergrain magnetic exchange coupling after annealing.