The invention relates to a system for cleaning modular belts, characterized in that it comprises a support structure configured to be mounted and dismounted from the structure of a modular-belt conveyor, wherein a plurality of cleaning stations are mounted on the support structure, said cleaning stations consisting of: (a) a first surface cleaning station consisting of at least one roller with cleaning flaps disposed crosswise on the modular belt; (b) a cleaning preparation station consisting of at least one transverse duct disposed in an elevated manner with a plurality of ejection nozzles distributed along the length of the at least one duct and along the width of the modular belt in order to sprinkle water in the form of a spray directly on the modular belt; (c) a pre-cleaning station comprising a system of at least one self-adjustable plastic scraper; (d) a second surface cleaning station consisting of at least one pair of rollers with cleaning flaps, one being placed on the upper part of the modular belt and the other on the lower part thereof; (e) a deep-cleaning and sanitization station consisting of a system of rotary steam-spraying heads connected to a dry steam generator; and (f) a station for drying with warm air, formed by at least two air turbines with an elevated transverse diffuser.