An analytical method was developed for the rapid determination of ²²⁶Ra in water through liquid scintillation counting. The separation and purification of ²²⁶Ra from water were performed by co-precipitation using barium sulfate as the carrier; the direct measurement of ²²⁶Ra was realized by using a liquid scintillation spectrometer. Through sample analysis, a mathematical model for uncertainty evaluation was established and the sources of uncertainty were analyzed. The results showed that the overall counting efficiency of ²²⁶Ra is 91.3%-98.5%, the detection limit is 0.01 Bq/L, and the relative extended uncertainty is 7% (k=2), indicating that the proposed method is suitable for the rapid analysis of ²²⁶Ra in drinking water. The uncertainty of the method for the determination of ²²⁶Ra in water is mainly caused by the errors of sample counting rate and overall counting efficiency.