Abstract: The liquid scintillation counting analyzer is used to determine the α-activity of Pu adsorbed in silica gel. The influences of preparation conditions and measuring parameters were studied. In order to determine the α-activity of Pu in silica phase, less than 1 g of silica gel was added into a 20 mL scintillation vial with 10 mL of cocktail. After 5 min of stirring, samples were measured by liquid scintillation analyzer. The activity of Pu in the vial equals to the total counts in energy window of 300-800 channel. The influences of HNO3, Fe, Zr, Nd on Pu analysis were studied. The formation of spectrogram was also preliminarily analyzed.