This paper presents a new explanation of why the growth effect of inflation reported in the literature is an inverted-U relationship with considerations of lower bound on bank lending rates. We integrate a non-zero lower bound on the lending rate in the discussion and show the effect of inflation on optimal bank loan contracts. This paper believes that informational friction is a source of the negative relationship between inflation and growth when the loan rate constraint is non-binding. Besides, it finds out that once this loan rate constraint is binding, increasing inflation can reduce the real cost of financing capital investment and then contribute to growth. This paper also proves that the non-zero lower limit can only be reached at t...