The invention discloses a forming platform for a 3D printer. The forming platform comprises a base, wherein a platform is arranged at the upper end of the base, a rotary disc is arranged at the middlepart of the platform, connecting rods are symmetrically arranged at the side ends of the rotary disc, and the outer side ends of the connecting rods are connected with a carrier stage; a supporting seat is arranged under the carrier stage, ejecting needles are arranged at the upper end of the supporting seat at intervals, the upper ends of the ejecting needles penetrate into and extend out of theplatform; a magnet is arranged at one side in the platform, a driving motor is arranged at the other side in the platform and is in drive connection with a rotary shaft the rotary shaft is arranged in the platform and is eccentrically provided with a jacking wheel which can extend out the platform and contacts with the supporting seat; a vertical column is arranged at the upper end of the platform and at one side of the carrier stage, and is provided with a cylinder; a piston rod of the cylinder is connected with a horizontally-arranged fork frame. The invention aims at providing the formingplatform for the 3D printer, and products can be quickly taken down from the platform.