The present invention is to provide a fixed base assembly of mobile phone, which comprises a base having a cylinder at its center, a hollow at its bottom being connected to the cylinder such that the base is sheathed into a pillar at the center of a sucking disc, a spring surrounding the periphery of the pillar such that the base can expand and contract along the pillar and allowing a rotary member to be disposed on the cylinder and an extended position of the base, a flange substantially having a wave-shaped height and being symmetrical along the periphery, such that the two flanges respectively having a wave valley and a wave peak, a peg being used to be inserted into a pair of corresponding rectangular apertures of the cylinder to pivotally couple the sucking disc pillar, rotary member, and base, and both ends of the peg being exposed from the flange.