In order to make the orbital angular momentum (OAM) mode generated in the optical fiber more integrated, a method to generate the orbital angular momentum mode using photonic crystal fiber (PCF) is proposed. By designing a special PCF, the transmission speeds of the eigenmodes of the odd and even modes are different, and thus a π/2 phase difference is formed after transmission for a certain distance to produce an OAM mode. The PCF is composed of a central air hole, a silica ring layer and an outer cladding layer. The outer cladding layer is composed of two layers of circular air holes. The number of circles in each layer is 2n+2, corresponding to the n-order OAM mode. The finite element method was used to carry out three-dimensional numerical simulation analysis of the designed optical fiber, and the +2, +3, +4, and +5 orders of OAM modes were successfully generated. The PCF method for generating OAM modes meets the trend of future integration and miniaturization for optical fiber communication systems, and has potential application prospects in all-fiber mode division multiplexing systems.