The invention discloses a laptop bag with a built-in laptop bracket. The laptop bag comprises a hollow bag body, wherein a heat dissipation plate framework is arranged in the bag body; a heat dissipation plate is fixed in the heat dissipation plate framework; through holes are formed in the heat dissipation plate; a movable rod is symmetrically hinged to each of two sides of the heat dissipation plate framework; the end part of each of the two movable rods is hinged to a connection rod; the end part of each of the two connection rods is connected to a unidirectional buckle assembly; an external keyboard supporting rod is arranged below the end part of each of two sides of the heat dissipation plate framework; and a wrist base plate is arranged at a position, which is located between the two connection rods, below the two external keyboard supporting rods. As the heat dissipation plate connected with an external keyboard frame is arranged inside the hollow bag body, a laptop, the heat dissipation plate and an external keyboard can be packed together; therefore, the laptop bag is compact in structure and convenient to carry; and moreover, by the arrangement of the wrist base plate conforming to human engineering, the use comfortableness is improved, and the angle, the height and the length can be all adjusted; the laptop bag is wide in application range, high in practicability and worthy of being widely popularized.