Abstract: OBJECTIVES To investigate kinetic characteristics of extraction process of iridoid glycosides from Ajuga decumbens. METHODS Colorimetric method was used to determine the contents of iridoid glycosides by water extraction. The Fick's law of diffusion was used to establish the kinetics equation of iridoid glycosides extracting parameters. The extraction was analyzed to obtain kinetics parameters, such as K (rate constant), E_a (activation energy), and t_1/2 (half life). RESULTS The experiments for extracting iridoid glycosides from A. decumbens were studied under different conditions to evaluate the kinetic equation based on Fick's first law of diffusion. Experimental data could match the kinetic equation with its apparent activation energy as 45.18 kJ·mol^-1. CONCLUSION The results show that the kinetics on the extraction of iridoid glycosides match the first-order rate equation.