The invention discloses an interference suppression method for a multi-user 
MIMO collaborative 
relay system, mainly solving the problem that each user has multiple antennas in a common-channel multi-user 
relay system. The interference suppression method comprises the steps that: a user determines a 
beamforming vector by adopting a 
signal space alignment method, and sends out a 
signal after weighting the 
signal with the 
beamforming vector in a multiple-
access time slot; a 
relay constructs a 
precoding matrix based on an orthogonal 
projection principle, and amplifies and sends the received signal after 
precoding; the user receives the signal and suppresses interference signals between user pairs by adopting a decoding vector, and conducts a 
maximum likelihood detection to obtain the needed signal. According to the invention, a network 
transmission rate and a 
resource utilization rate are improved, diversity gains of multiple antennas are achieved, channel 
fading resisting capability of the 
system is enhanced, and a bit 
error ratio is decreased. Further, the interference suppression method of the invention can be applied in a transmission mode under 
centralized management and control of a 
wireless ad hoc network and 
base station, wherein data can be exchanged directly through user-relay-user mode.