Abstract: The method of measuring β particle of ~(147)pm directly in the solution which contains α-hydroxy isobutanoic acid (α-HIBA), HNO_3 and ~(241)Am is described in this report. The effect of scintiliquid(PPOPOPOP-naphthalene dioxane) and α-HIBA and HNO_3 on the measurement of ~(147)Pm is studied. The effect of ~(241)Am on the measurement of ~(147)pm is also studied. Relative counting efficiency in the measurement of ~(147)Pm for several measured solution is determined. If the activity of ~(147)Pm and ~(241)Am is about the same in the sample, they can be measured at a threshold of 1.40—5.35 V and 6.00—7.40 V respectively and interference is smaller than 1％. Absolute content of ~(147)Pm in 12 samples of high-level liquid waste was measured by this method. The results are satisfactory. The relative standard deviation of measurement for the same kind of samples is<1％.