A device for cleaning a conveyor belt soiled with fluid substances, and in particular for machines used for spraying paint or other products, is disclosed. The conveyor belt has an upper section and a lower return section comprising a (a) reverse roller in contact with the return section of the belt to collect the fluid substances on the belt; (b) doctor blade for scraping the fluid substances collected from the reverse roller; (c) at least one secondary belt conveyor mounted on a pair of supporting rollers and disposed beneath the doctor blade for collecting the fluid substances from the doctor blade and for conveying the fluid substances toward one end of said secondary belt conveyor; and (d) means at the end of the secondary belt conveyor for scraping the fluid substances from the secondary belt conveyor and for conveying the substances to a final collection and/or recycling means.