8PSK modulation methods and apparatuses are provided. In a first embodiment, product factors of symbol vectors and a coefficient of a shape filter are stored in a table and compressed by 8 times based on a law of a trigonometric function, wherein a method of table looking-up is used to replace a multiplication operation. In a second embodiment, all states of 8PSK modulation are stored in a table after shape filtering, and then the data of the states stored in the table are compressed based on a corresponding relationship of a law of a trigonometric function and an electrical level diversity, and then a table looking-up operation is performed. In a third embodiment, new modulated vectors are stored in a modulated phase table after simple 8PSK modulation and phase rotation, the modulated phase table is compressed by 4 times, and new modulated vectors are obtained by a table looking-up operation and data processing. Then, shape filtering is performed by utilizing a RAM coefficient filter. The 8PSK modulation methods and apparatuses are compatible with GSM systems and are capable of providing sufficient capability of data services and sufficiently extending a life cycle of prior GSM systems. It allows a service agent not only to save investment, but also to provide competitive services.