To investigate the capillary transport mechanism of microcapsule core material （epoxy resin） to repair micro-cracks in cement-based materials， the contact angle and surface tension of epoxy resin were measured by optical contact angle measuring instrument. Environment scanning electron microscopy （ESEM） was used to observe the wetting effect of epoxy resin on the crack surface of cement-based materials. To study the influence of temperature， crack width， epoxy resin and other factors on capillary transport capacity， a theoretical model of capillary flow was established and conducted a simulated capillary flow test. The results show as follows： in the range of 20-50 ℃， increasing temperature can reduce epoxy resin viscosity and enhance the capillary transport capacity of micro-cracks in cement-based materials. When epoxy resin permeates through narrow cracks （generally less than 200 μm）， its gravity can be ignored in the initial stage， and the driving force is generated by capillary force. In the range of 50-200 μm， epoxy resin capillary transport capacity is inversely proportional to crack width， the smaller the width， the more obvious the capillary force and the stronger the capillary transport capacity. The capillary transport capacity of epoxy resin E-51 is 17.4%， stronger than epoxy resin E-44， the capillary transport capacity of fluorescent epoxy resin is 5%-8% lower than epoxy resin.