In order to validate and analyze the reliability of Biot number-lag factor (Bi-G) correlation to estimate convective mass transfer coefficient and moisture diffusion coefficient of biological material under hot air drying, the drying experiment data of carrot slice is fitted by the exponential function, and the convective mass transfer coefficient and the moisture diffusion coefficient are estimated by Bi-G correlation. Then, the estimated values are used to simulate moisture change of carrot slice in the drying model, in which the internal moisture diffusion follows the Fick’s second law of diffusion, and the mass transfer between the biological medium and hot air follows the convective boundary condition. The calculated values are compared to the drying experiment data. The results show that the exponential function fitting drying experimental data well is not the sufficient condition for the Bi-G correlation to accurately estimate the convective mass transfer coefficient and the moisture diffusion coefficient. Bi-G correlation can not be used to accurately estimate the convective mass transfer coefficient and the moisture diffusion coefficient. 