As bone substitute materials, most commonly used calcium phosphates exhibit relatively low bioresorption rates. Most calcium sulfates exhibit relatively low mechanical strength and excessively high dissolution rates. The structure and properties of tetracalcium phosphate (TTCP)/dicalcium phosphate anhydrous (DCPA)/calcium sulfate hemihydrate (CSH) cement immersed in Hanks’ solution are investigated in the present study. Results indicate that this cement has a working time of 6.6 min and setting time of 7.7 min. The maximum compressive strength is obtained when the cement is immersed in Hanks’ solution for 1 day, at which point the TTCP/DCPA-hydroxyapatite (HA) phase transformation has been largely completed. The long-term pH value of the Hanks’ solution wherein the cement is immersed remains between 6 and 7. The HA phase remains the dominant phase throughout the entire 42 days of immersion.