Abstract: The effect of moisture conditioning treatment parameters of brown rice on the water absorption rate of polished rice was studied based on isotope tracing. The added water in brown rice was located by isotope tracing of H₂³O. The cpm level of absorbed water in polished rice was assayed by radiometric. The method of quadratic orthogonal rotation combination experiment design was applied. The regression equation on the effect of the parameters on the water absorption rate of polished rice was obtained by analyzing the test data with Software Reda. The results provide theoretical basis for controlling water contents of polished rice after the brown rice moisture conditioning treatment.