A cleaning brush structure comprises an outer sheath mounted to the outer side of an inner sheath, and an actuating body wherein the outer sheath has an elongated positioning slot communicating with an insert hole of the inner sheath for the engagement of an insert portion of the actuating body therewith. Both inner longitudinal edges of the positioning slot thereof has protrusive points and concaved points alternatively arranged in a symmetrical manner thereon to form narrower restraining space and wider accommodation space for stable location of a positioning section of the insert portion to provide a stepwise adjustment effect thereby. The actuating body also has a guiding push plate of various pattern attached thereto, and depending on the depth and area of the article to be cleaned, the inner sheath can be adjusted stepwise to ensure an accurate extension of a brush body released for the cleaning operation thereof.