Abstract:The effects of water reducing admixture of ordinanry Portland cement(OPC) on the fluidity of magnesia-phosphate cement(MPC) based material were studied.The effects of the compound water reducing admixture,which were made up by complex technology based on the character of MPC,on the fluidity,setting time, strength,hydrates and micrograph of the magnesia-phosphate cement-based material was discussed.The experimental results show that the water reducing admixtures which suit to the OPC increase the fluidity of MPC mortar little,sometime even decrease the MPC mortar fluidity.But the compound water reducing admixture can improve notably the fluidity and strength of the MPC mortar and concrete much.The compound water reducing admixture can increase the content of hydration products and the microstructural development of MPC too.