Provided is a method and apparatus for lattice reduction with reduced computational complexity. The apparatus and method include calculating an R matrix using sorted QR decomposition, and conducting an R-value test using an R-value based on diagonal elements of the R matrix and a threshold value. The R matrix is an upper triangular matrix. The apparatus and method further execute a loop comprising a size reduction and a conditional update of a basis vector corresponding to a column element of the R matrix in response to the R-value being greater than or equal to the threshold value. The apparatus and method conduct another R-value test based on the R matrix comprising the updated basis vector in response to the basis vector being updated.