The invention discloses an automatic carbon fiber sheet reinforcement construction device suitable for a variable cross-section ribbed structure. The automatic carbon fiber sheet reinforcement construction device comprises a gluing pasting module installed slidably, and the gluing pasting module can be used for brushing an adhesive and pasting a carbon fiber sheet on the surface of a component. Inorder to adapt to the variable cross-section structure, the side face of gluing pasting module comprises a cutting device which can walk along the cross section. The cutting device comprises a spring, a roller is installed on the spring, the roller is located between a gluing roller and a carbon fiber sheet roll, and a cutting blade is installed on the roller and is not rotated with the roller and used for cutting the sheet roll. The automatic carbon fiber sheet reinforcement construction device suitable for the variable cross-section ribbed structure can solve the complex problem of carbon fiber sheet pasting in construction, comprehensively strengthens the carbon fiber sheet of the complex cross-section (mainly ramped variable cross-section ribbed structure) structure, the degree of automation is high, construction quality is stable, the device is portable, the operation of worker is facilitated.