The invention relates the switching position and adjusting pitch device and adjusting method used for adult incontinence trouser, adult urine trouser, flap sanitary napkin and pad. The mother wheel which has more than two trepan borings is looped on chief axis, more than two inside spin guide groove bush is in radial trepan borings of chief axis, more than two guided stems is in inside spin guide groove bush, the pins are installed on guided stems and rotate along with inside spin guided groove, the upper end of guided stem is connected with the back of negative pressure box, the transverse guided stem is fixed by guided stem through axle sleeve, and the guide head of transverse guided is in guided groove of guided wheel. The invention has the following advantages: realizing the pitch automatic adjustment in the production process of adult incontinence trouser, adult urine trouser, flap sanitary napkin and pad, avoiding breaking the cotton fiber; the structure being novel style, unique, simple, exact, reliable and practical.