Provided is a processing method and apparatus for performing space-time decoding on MIMO signals. The method includes: performing QR decomposition on a channel matrix H with a size of Nr×Nt in a MIMO system and performing an initialization operation, wherein Nt is the number of transmitting antennas and Nr is the number of receiving antennas; enumerating candidate constellation points of transmitting signals at each level of transmitting antennas according to an input parameter M=[M1, M2, . . . , MNt], a receiving signal y and a result of QR decomposition of H, wherein M is the number of the numerated candidate constellation points at each level, y=Hs+n; calculating increments of a Euclid distance due to addition of selection of a candidate constellation point at present level according to obtained candidate constellation points; and deciding and outputting space-time decoding according to the sum of calculated increments of Euclid distances of candidate constellation points at all levels.