This article takes listed companies which disclose R&D expenses continuously in 2004-2009 as subject and tests the reciprocal relationship between R&D inputs and profitability empirically by using panel data model. The result indicates that R&D input has remarkable positive influence on profitability of current period、one year’s lag phase and three years’ lag phase. The contribution of R&D inputs on increase of profitability tends to reduce with the expansion of lag phase.