Abstract: In order to investigate the character of water transportation in cement-emulsified asphalt mortar (CA mortar) for CRTS (China railway track system) Ⅰ-type slab ballastless track (CRTS Ⅰ-type CA mortar), changes in the contact angle of water and mass of capillary water adsorption with time were tested, and the SEM (scanning electric microscopy) and EDS (energy dispersive spectrometer) were used to detect the fracture surfaces of the CA mortar. The research results show that like a normal porous material, the mass of capillary water adsorption of the CA mortar has a linear relationship with the extraction of time. The “sandwich structure” of the interface between CRTSⅠ-type CA mortar and a pouring bag is the reason for the large decrease of the capillary water adsorption coefficient. From the SEM analysis, an asphalt-rich film can be formed on the surface of the CA mortar by polishing to increase the contact angle of water and reduce about 45% of the capillary water adsorption coefficient. In addition, the nature fracture surface of the CA mortar at the perfusion port should be processed during the construction.