The magnetic properties and microstructure of sintered iron-phosphorus and iron-silicon-phosphorus compacts have been investigated. Measurements of maximum permeability (μ_max) and coercive force (Hc) were performed with a hysteresisgraph tracer. The densification rate of iron powder with phosphorus was greater than that of pure iron powder. At the same sintering temperature, the increased phosphorus content in iron caused B_(10), Br, μ_(max) to increase and He to decrease. In Fe-3w/o Si-P system, the addition of phosphorus enhanced the sinterability but decreased μ-max and increased Hc. These phenomena were discussed in terms of pore distribution, the formation of secondary phases in the grain and the formation of amorphous phase in the grain boundary. The resistivities of sintered compacts were increased with the increase of the amount of phosphorus in both the Fe-P and Fe-3w/o Si-P systems.