Abstract: A cradle base collapsible mechanism, involving four sides at the bottom of a baby cradle, each side involving two support rods that are joined by a middle unit, each corner of the cradle involving a corner piece that is joined to another end of the support rod, the inside of each middle unit is joined with a middle rod, the other end of the middle rod is joined to one side of a center unit, one end of the middle rod facing the center unit is fitted with a bottom fixing unit, the fixing unit has a flange that is engaged to the rod opening, to the fixing unit is riveted a slide block, between the slide block and the fixing unit bottom is a spring, the oblique section at the front end of each slide block extending a fixing unit, in connection with a corresponding end of a pressing plate, when the pressing plate is lifted, the slide block will retract, and the middle rod will be pulled up and straightened accordingly, then the middle unit will be folded ninety degrees, so each support rod is pulled up and straigh