A fastener-free box with fast assembly comprises a baseboard, a front board, a rear board, a left board, a right board, and a cover board. An insert-connection structure that is configured to form an insert connection with a respective adjacent board is integrally formed on each of the board; and, a connection structure configured to couple with each other is integrally and individually formed on each of the cover board and the rear board. The structure of the box is simple. In addition, an interlocking structure can be formed after the box is assembled, enabling a robust box structure. Furthermore, the box is ideal for outdoor use as it is water proof.