Provided are a method and an apparatus for detecting a thickness of parer, and a storage medium. The method includes: acquiring a first thickness image of a target paper; extracting at least one first thickness feature and at least one second thickness feature from the first thickness image in the first thickness image; performing average processing on gray values of multiple pixel points in the at least one first thickness feature to acquire a first gray value, and the average processing is performed on gray values of the multiple pixel points in the at least one second thickness feature to acquire a second gray value, when the first gray value is, smaller than the second gray value of multiple pixel points in at least one second thickness feature, determining that a thickness of a region, corresponding to the at least one second thickness feature, on the target paper has changed.