Abstract: A bike multi-functional rainproof assembly comprises a foldable frame having a foldable tube; a front end of the foldable tube being installed with a joint for connecting with a quick connecting rotary seat; a box having a front end combed with a rear retaining frame; the rear retaining frame for connecting to a rear side of a bike seat; the box having a lock and a ring; releasing the ring, a box bottom can be opened; the box bottom being installed with a telescopic rod set; and the telescopic rod set including a main frame, a movable rotary seat, a quick connecting rotary seat, a telescopic frame, and a sub-telescopic frame; the sub-telescopic frame being installed with a waterproof cloth; after the interior components of the telescopic rod set is expanded and fixed, the waterproof cloth having the effect of waterproof.