The utility model relates to a pen-shaped anti-riot pistol, which comprises a casing, an ignitor, a switch, and a bomb cavity, wherein, the ignitor is positioned at the back part of the casing; an igniting head is positioned at the back end of the bomb cavity; the bomb cavity is arranged in the casing in an eccentric way; the inner part of the casing is provided with a sliding chute which is used for the switch to slide; the back end of the switch is contacted with the movable end of the ignitor; the front end of the bomb cavity is provided with the locking mechanism of the bullet. The utility model has the advantages of simple structure, compact structure, reasonable structure, good invisibility, convenient operation, and one object with multifunction. The utility model is a security weapon which is carried and used frequently by the persona, such as the criminal arrestment, the counterattack hijacking, the violence prevention, the public security, etc.