The present invention discloses a glass fiber-reinforced flame retardant PBT composition which includes following components in parts by weight: 35 to 71 parts of a PBT resin; 5 to 30 parts of a flame retardant; and 5 to 50 parts of a glass fiber; based on a total weight of the glass fiber-reinforced flame retardant PBT composition, a content of tetrahydrofuran is less than/equal to 500 ppm and more than/equal to 10 ppm. In the present invention, when the content of tetrahydrofuran which is selected to be added in a formula of the glass fiber-reinforced flame retardant PBT composition, is less than/equal to 500 ppm and more than/equal to 10 ppm based on the total weight of the glass fiber-reinforced flame retardant PBT composition, a flowability and injection molding appearance of the glass fiber-reinforced flame retardant PBT composition can be apparently improved.