Abstract: This paper investigates the relation between R&D investment and risk of stock price crash. The results show that firms' R&D investment significantly increases the risk of stock price crash，which is only exists in firms with excessive investment in R&D. The proportion of shares holding by the largest shareholder significantly inhibit the positive relation between R&D investment and risk of stock price crash, which mean supervision mechanism of large shareholders is functioning. Further studies show that there exist partial channels of cash holding and tax avoidance and the positive relationship between R&D investment and risk of stock price crash is only significant in firms with non-Big 4 auditors, low cash holdings and non-high-tech industry. The conclusion deepens the understanding of negative economic consequences of R&D investment. It is practically meaningful for promoting the development of capital market.