A novel phosphate bonded magnesia cement was developed recently, which sets quickly and develops high strength in the early ages. In the present research, the physical and mechanical properties, hydration products, and microstructure of the new cement were investigated. The new cement was mainly consists of dead burned magnesia, phosphate and fly ash. The results showed that it not only has high early strength, but also has high long-term strength. Interestingly, the strength of the cement increase with the content of fly ash, from 10 % - 40 % by weight. The hardened cement paste has a dense microstructure, low open porosity and water sorptivity due to the low water to binder ratio. The reaction products after hydration of the cement includes struvite mineral and amorphous species.