The invention discloses a method and a base station for phase compensation in beamforming in a multi-antenna Time Division Duplex (TDD) communication network. In a first transmission mode, e.g. TM4 or TM8, the base station estimates a first phase shift between a first antenna port and a reference antenna port in uplink based on a measurement of a first Sounding Reference Signal (SRS). Then the base station estimates in the first transmission mode a second phase shift between the first antenna port and the reference antenna port in downlink based on a Channel State Information (CSI) feedback from a User Equipment (UE), and calculates a parameter indicative of a difference between the first phase shift and the second phase shift. In a second transmission mode, e.g. TM7 or TM8, the base station estimates a third phase shift between the first antenna port and the reference antenna port in uplink based on a measurement of a second SRS, and calculates in the second transmission mode, a fourth phase shift between the first antenna port and the reference antenna port in downlink as a difference between the third phase shift and the parameter. The base station then compensates in the second transmission mode, the phase of input signal on the first antenna port by the fourth phase shift for beamforming.