The equilibrium distribution coefficients of 12 impurities (As, Fe, Ca, Co, Al, Cr, Cu, Mg, Mn, Ni, Pb, Zn) in phosphorus were obtained by measuring their effective distribution coefficients at zone travel rate of 3, 5, 10, 15, and 20 mm.h(-1) in the purification process with vertical zone-melting technique. The results indicate that the method is reliable. The equilibrium distribution coefficients are below 0.3 except arsenic.