The objective of this study was to develop anti-washout and fast-setting calcium–magnesium phosphate cement (as-CMP) by introducing white dextrin (WD) and magnesium phosphate cement (MPC) to CPC. The results showed that WD imparted anti-washout to the as-CMP paste, whereas MPC simultaneously improved the paste anti-washout and fast-setting. The synergistic effect of MPC and WD obviously shortened the setting time of as-CMP. The WD did not affect the phase evolution and microstructure of the paste. Furthermore, all samples were biocompatible and as-CMP exhibited the best cell metabolic activity, cell attachment, and proliferation, which would provide basic data for the clinical application.