The effect of applying urea, biological fertilizer and urease inhibitor to rice on the N-transformation was studied.The result showed: The urease activity persistence and urea hydrolyzation were all changed with the using dosage of urease inhibitor, and the urease activity was increased as time increased. When added bio-fertilizer, the number of soil microorganism and urease activity were all increased but the inhibitor ability was decreased . The rice yield was increased by 9.83% -21.02%.