A folding drawer includes a bottom board; two side panels each including a slide and an L-shaped positioning member on a top of a rear end; a rear panel including two U-shaped grooves on two sides respectively, and two flexible projections each adjacent to the U-shaped groove wherein the L-shaped positioning member is configured to dispose in the U-shaped groove; a front panel; a first hinge on a joining portion of a rear surface of the rear panel and a bottom of the bottom board, a second hinge on a joining portion of an inner surface of one side panel and a top of the bottom board, and a third hinge on a joining portion of an inner surface of the other side panel and the top of the bottom board.