Abstract: Time-dependent self-diffusion coefficients and magnetization attenuation of liquid with surface relaxation in porous media in an infinitely long cylinder are calculated with Monte Carlo random walk method.Relationship between parameters of NMR relaxation and random walk is obtained.In fast-diffusion area, magnetization of nuclear spins attenuates exponentially,and self-diffusion coefficients are independent of surface relaxivity within short diffusion time.In slow-diffusion area,both magnetization attenuation and self-diffusion coefficients are independent of surface relaxivity within short diffusion time.These results agree well with theoretical analysis.Surfaceto-volume ratio and pore size can be determined.

Key words: self-diffusion, surface relaxation, magnetization attenuation, Monte Carlo simulation