To measure the level of gross α radioactivity for drinking water source in Lasa and evaluate the uncertainty in the measurement, some water samples have been measured based on industry standard methods. Regarding to these samples, the main sources and quantities of uncertainty in the measurements have also been analyzed and confirmed by calculation formula and uncertainty analysis experiments. The experimental results show that gross α radioactivity for drinking water source in Lasa is relatively low(≤0.05 Bq·L-1). The results of uncertaint...