A toilet chemical dispenser includes a housing defining an accommodation chamber and a first opening, a cover plate covering the first opening and having a water outlet port. a flow-guide plate upwardly outwardly extended from the cover plate and defining with the cover plate a predetermined contained angle, a chemical box accommodated in the accommodation chamber of the housing and having a second opening facing the first opening and the water outlet port of the cover plate, and a mounting device having its one connected to the housing and its other end thereof for fastening to the top edge of the bowl of a toilet.