The invention provides a linear variable gain power amplifier working at 915MHz. The linear variable gain power amplifier comprises a driving stage circuit of a cascode structure and a power stage circuit of a cascode structure, which are serially connected in sequence, wherein an input end of the driving stage circuit is separately connected with an external radio frequency input signal and a grid active bias circuit, the input end of the power stage circuit is further connected with a linear grid bias circuit, and an output end of the power stage circuit is connected with a load. According to the linear variable gain power amplifier working at 915MHz provided by the invention, the driving stage adopts three cascode structures connected in parallel, and the grid voltage switches sharing the grid are converted to achieve adjustable gain and the output power. Moreover, by means of the grid bias structure, a stable voltage can be obtained, and capacitance compensation can be further obtained to improve the linearity of output signals.