Theoretical formula of scintillation intensity temporal frequency spectrum is presented under oblique incidence and anisotropic irregularity conditions.The theoretical results show that the low-frequency part of spectra are controlled by propagation geometry when irregularities are anisotropic.The propagation angle is thought to be a important factor.Finally,the theory is applied to interpret the VHP signal scintillation data received from the ETS-II at Xinxiang,Wuchang the Guangzhou and the theory correctly predicts the low frequency spectral shapes.