This study aims to investigate the fracture behavior of cement mortar with fly ash(FA) at early age. Five mass fractions (0%, 10%, 20%, 30%, and 40%) of fly ash were used to replace cement, and 45 cement mortar notched beams were prepared in the laboratory. Three-point bending fracture tests and compressive tests were conducted on the specimens after curing for 1, 2 and 3 days, respectively. Digital image correlation (DIC) technology was adopted for real-time monitoring, while acoustic emission(AE) technology was used to record the occurrence and accumulation of internal damage. The results show that FA lead to an obvious decrease in the fracture behavior and compressive properties of cement mortar at early age. Meanwhile, the incorporation of FA result in the reduction of fracture resistance for cement mortar at early age. It is worth noting that both the fracture process zone and the internal damage range are significantly narrowed for FA cement mortar at early age. It is demonstrated that with the increase of FA content and shortening of curing age, the fracture parameters of the cement mortar decrease, while the cracks propagation accelerates. It is found that a linear relationship exists between fracture parameters and cube compressive strength.