We consider 1d random Hermitian N × N block band matrices consisting of W × W random Gaussian blocks (parametrized by j, k ∈ Λ = [1, n] ∩ Z, N = nW ) with a fixed entry's variance J jk = W −1 (δ j,k + β∆ j,k ) in each block. Considering the limit W, n → ∞, we prove that the behaviour of the second correlation function of such matrices in the bulk of the spectrum, as W ≫ √ N , is determined by the Wigner -Dyson statistics. The method of the proof is based on the rigorous application of supersymmetric transfer matrix approach developed in [20].