The invention relates to a pattern forming method, a method for manufacturing a magnetic recording medium and a magnetic recording medium. The self-assembled membrane is used to form fine patterns with a high density. According to the application mode, the working procedure described in the description is performed for 2 to 3 times repeatedly so as to increase the density of protruded patterns compared to the one-layer diblock copolymer layer; wherein the working procedure is carried out to form diblock copolymer layer, the phase separation is performed to obtain sea island phase, and then etching is performed on the sea island phase.