The propagation characteristics of terahertz wave in non-magnetized and non-uniform plasma sheath are studied by the Scattering Matrix Method(SMM). The terahertz wave power reflection, transmission and absorption are simulated when the wave obliquely radiate the plasma, given that the electron density distribution of the plasma sheath is in double-exponential distribution. The variations of the terahertz wave power reflection, transmission and absorption with incident angle, terahertz frequency, plasma collision frequency and plasma distribution shape are summarized. The numerical results show that the terahertz wave has good propagation characteristics under these conditions. Overall, the transmittance of terahertz wave is better in plasma as its frequency increases, therefore, increasing the carrier frequency to terahertz band can be considered for solving blackout problem.