Abstract: Magnetic intergranular interactions and other magnetic properties of perpendicular magnetic recording films can be judged by Delta-M curves. The magnetic properties of Co23Pt77 perpendicular magnetic recording film prepared by direct current magnetron sputtering method were characterized by using vibrating sample magneto-meter (VSM，Lakeshore7407). The measurement techniques and demagnetization factor correction of isothermal remanent magnetization (IRM) and direct current demagnetization remanence (DCD) of perpendicular recording media were presented in detail. Corrected methods of demagnetization field were determined. In addition, the calculation methods of Delta-M curve from corrected demagnetization IRM curve as well as DCD curve were introduced.