A field effect transistor and a manufacturing method thereof are provided. The field effect transistor includes two top gate structures (1031C and 1031D) and two bottom gate structures (1032A and 1032B). The top gate structures (1031C and 1031D) and the bottom gate structures (1032A and 1032B) are opposite to each other in pair. This increases a quantity of control-voltage-induced carriers in the field effect transistor, and therefore increases an output current of the field effect transistor, improves a power gain limit frequency in high-frequency use, and makes an electric field between the top gate structures (1031C and 1031D) and the bottom gate structures (1032A and 1032B) more adequately cover a channel layer (106) between source structures (1041 and 1042) and a drain (105), thereby reducing a parasitic effect in a high frequency, and further improving a frequency characteristic of the field effect transistor.