With A-shared listed companies in Shanghai and Shenzhen stock exchanges from 2007 to 2013 as a sample, this paper studies the relationships between cash holdings and R&D investment. The empirical results show that companies with more business R&D investment will increase cash holdings level; the companies with more initial cash holdings will have more R&D investment, which reflect the significant sensitivity of R & D cash flow. With the cash holdings increased, the sensitivity will decrease. Compared to the companies in mature stage, the cash holdings in companies in growth stage are positively correlated with R& D investment, the sensitiving of its R & D cash flow will not decrease with the increase of cash holdings.