We propose a novel approach based on the inversion method to eliminate interference in the continuous-wave (CW) terahertz (THz) reflection imaging. Through the study on the imaging window of the CW-THz reflection imaging with the interference mechanism, inverse processing is introduced to realize the interference elimination. Based on the theoretical calculation, high resistivity float-zone silicon (HRFZ-Si) with high refractive index is selected as the imaging window to improve the dynamic range of the THz image. The interference elimination method is verified experimentally by a CW-THz reflection imaging system based on a THz quantum cascade laser (QCL) lasing at 4.3THz. The reflectivities of liquid samples of water and ethanol are restored by the interference elimination method, which corresponds well with the theoretical calculation. Moreover, the interference elimination method is performed on THz images of fresh biological tissues. The image contrast of tissue can be greatly enhanced with the accurate reflective information.