In order to study the effect of composite minerals on the fracture properties of cement mortar at early age, the fracture behavior of cement mortar compounded with four types of fly ash admixture (0%, 15%, 30%, 45%) and four types of nano-partitioned kaolinite (1%, 3%, 5%, 10%) at early age (1, 3, 7, and 28 d) was carried out. Based on three-point bending experiments, the load-crack opening displacement curves, critical crack extension, double-K fracture toughness, and fracture energy of cement mortar center-notched beams were analyzed, and the relationship between their compressive strength and fracture toughness and fracture energy was established. The results show that the peak load of cement mortar notched beams at an early age shows a decreasing trend with the increase of FA (fly ash) mass fraction; The incorporation of fly ash not only reduces the fracture toughness of mortar but also has a more significant effect on the reduction of the destabilizing toughness. With the increase of fly ash admixture, the fracture energy of cement mortar notched beams at an early age show a tendency of increasing first and then decreasing. The peak load, fracture toughness, and fracture energy of cement mortar notched beams at an early age show a trend of increasing and then decreasing after compounding with nano-partialized kaolin; At the age of 1 day, 1% mass fraction of NMK(nano-metakaolin) enhance the peak load by a maximum of 23.9%; and when 5% nano-partialized kaolin is doped, the effect of the fracture energy enhancement at the age of 7 days is a maximum of 52.9%. The starting cracking toughness, destabilizing toughness, and fracture energy of cement mortar notched beams at an early age had a linear increase with the increase of compressive strength, and their correlation coefficients were not less than 0.81, and the correlation with nano-partialized kaolin was better than that with fly ash alone.