An endoscope with a T-shaped flexible circuit board includes: a base mounting frame, a flexible circuit, a photosensitive element, two light emitting elements and a camera. The photosensitive element, the two light emitting elements and the camera are mounted onto the T-shaped flexible circuit board, then the flexible circuit board deforms to fit in the base mounting frame. During assembly, the photosensitive element, the two light emitting elements and the camera are maintained in the same orientation, and the T-shaped flexible circuit can be pushed into the base mounting frame simply by applying a force in a single direction parallel to the orientation direction of the photosensitive element, the two light emitting elements and the camera.