The high-magnesia and low-heat Portland cement (HMLHC) can significantly improve the anti-cracking and durability of mass concrete such as dams. Based on the X-ray powder diffraction (XRD), petrographic analysis, scanning electron microscope (SEM) and testing of strength (compressive strength) and expansion rate, the effects of calcination and cooling conditions, including calcination temperature, holding time and cooling rate, on mineral compositions and properties of HMLHC clinker were studied in this project. The results obtained from XRD, petrographic analysis and SEM qualitatively show that when the calcination temperature or cooling rate is improved or the holding time is prolonged appropriately, the C3S content in HMLHC clinker increases while the C2S content decreases, and the generation and growth of periclase crystals are promoted. Improving the calcination temperature, the later (after 28 days of curing) strength increasing rate of HMLHC decreases, and the HMLHC calcined at 1450 °C has the highest strength on 471 d, which is 86.57 MPa; the later expansion increasing rate improves, and that of the HMLHC calcined at 1500 °C is the highest, reaching 110.00%. Prolonging the holding time to 60 min from 30 min, the strength of the HMLHC on 28 d increases by 3.46 MPa. The HMLHC with the holding time of 60 min and under forced-air cooling has the highest later expansion increasing rate, reaching 106.25%.