This research introduces a new method to analyze the diffusion information of human brain. By use of the multi b value diffusion data and a new algorithm, a new diffusion parameter (Rd) was computed, and a new image was reconstructed. Through quantitative research on the brains of 25 normal adults, the new method can improve the signal-to-noise ratio (SNR) apparently and distinguish the different brain tissues effectively, compared to the apparent diffusion coefficient. The new method can improve the sensitivity to diffusion.