Abstract: The determination technique for the residual tritium in Pt-SDB hydrophobic catalyst with liquid scintillation counting method was studied. Pt-SDB hydrophobic catalyst sample was treated with 5A molecular sieve, and then heated under vacuum condition to remove the adsorption tritium. The sample was dissolved in the mixture of nitric acid and sulfuric acid in Advanced Microwave Labstation. The residual tritium of the tested sample is 1.69×10⁴ Bq/g, and the uncertainty of measurement is 10% (K=2).