Terahertz time-domain spectroscopic (THz-TDS) imaging is an interesting new tool for nondestructive testing and other applications. However, the current speed of image acquisition is relatively low, making it difficult to use for moving objects. In this paper, we propose a real-time THz-TDS line scanner based on electro-optical time-to-space conversion and line focusing of a THz beam. The proposed system functions as a color scanner in the terahertz spectral region with fast line-scanning and has been successfully used to image objects, which are moved on a translation stage. The achieved THz-TDS imaging rate is 23,200 pixels per second. This proposed THz-TDS line scanner has the potential to become a powerful tool for monitoring moving objects in various real-world applications.