The invention discloses a multi-cell beam forming method and a multi-cell beam forming device. The method comprises steps: with a principle of maximizing the signal intensity of a cooperative cell scheduling user and minimizing weighted interference leakage on other cooperative cell scheduling users by the cooperative cell scheduling user, a beam forming vector bq for each cooperative cell in a heterogeneous network is calculated; and based on the calculation result, a beam forming vector bq for the corresponding cooperative cell is updated to enable each cooperative cell to transmit data according to the updated beam forming vector bq and the corresponding scheduling user. The method of the invention is used for calculating and acquiring the beam forming vector for data transmission, the best balance between the system performance and the interference avoidance is achieved, effectiveness of interference management is improved, and the system capacity of a low-power node is further improved.