Abstract: For coping with the severe inter-cell intereference in the future cellular systems, this paper studies the collaborative multicell downlink transmission for multiusers in multicell systems. This paper proposes an iterative scheme to optimize jointly relay and the Base Station (BS) beamforming weights to maximize the worst-case Signal-to-Interference-and-Noise Ratio (SINR) under total relay and BS power constraints. The proposed optimization problems for relay and BS beamforming weights can be effectively solved by using the Semi-Definite Relaxation (SDR) technology. The simulation results show that the proposed relay and BS beamforming iterative scheme can achieve near-optimal performance within a few iterations for multiusers in multicell systems.