Based on wind tunnel tests of two square tall buildings, the characteristics of wind pressure spectra on the isolated and interfered building were investigated. Firstly experiments on a single square tall building in C terrain were carried out, then tests on the same building with 16 different locations and 3 different height ratios of an interfering building were conducted and wind pressures on the interfered building were obtained. In these foundations, the interference effects on wind pressure spectra of the typical taps of the interfered building were analyzed in frequency–domain with different spacing ratio and height ratio in tandem configurations. The results show that wind pressure spectra energy on the center line of the windward face of the isolated building is distributed over a wide frequency range; however, that near the edges on the face has sharp peaks. Energy at high reduced frequency near the trailing edges on the side face of the isolated building is significantly greater than that near the leading edges. The sharp peak amplitudes were dampened dramatically when the spacing ratio is small in tandem arrangements. The lower interfering building leads to larger energy at low reduced frequency, while the taller interfering building mainly affects the energy at high reduced frequency.