At normal temperature, the adsorption isotherm of urokinase on Zhejiang and Jiling diatomite surfaces was found to be type V and type II, resp.; both turned into III type after roasting. The adsorption isotherm type is concerned with the surface structure, pore structure, surface z elec. potential of diatomite. When diatomite was roasted at 400? the pI decreased to a min. value and the adsorption amount attained max. value. After the diatomite was modified, the adsorption amount also changed. The adsorption of urokinase on diatomite surface was also determine; its equation was consistent with the q/(1-q) = (Kc)1/b equation and the equilibrium constant K and adsorption function chain segments varying with temperature were discussed.

Key words: SURFACE STRUCTURE, DIATOMITE, UROKINASE, ISOELECTRIC POINT, ZETA POTENTIAL, SURFACES ADSORPTION