A detachable table tennis apparatus includes a playing table detachably mounted on a table, and a plurality of positioning devices mounted on the playing table to position the playing table on the table. Thus, the playing table is mounted on tables of different sizes to facilitate a user playing the table tennis. In addition, the fixing block is driven by the two movable plates to press or release the rim of the table so as to lock or unlock the playing table, so that the playing table is mounted on and detached from the table easily and rapidly. Further, the playing table is foldable when not in use to reduce the volume of the table tennis apparatus, thereby facilitating storage and transportation of the table tennis apparatus.