Abstract: Systemic risk is an important factor driving stock market price fluctuation. Different stocks often have different falling and rising amplitude during and after the systemic risk shock. As a comprehensive index reflecting the market competitiveness and profitability of listed companies, enterprise innovation ability is bound to have an important impact on the intrinsic value of their stocks and trading behavior of investors, which may cause different stock price to present different volatility under the same systemic risk shock. Therefore, exploring the impact mechanism and empirical evidence of systemic risk shock and enterprise innovation ability on stock price volatility not only helps to clarify the reasons why different stocks present different price stability under the same systemic risk shock, but also may provide theoretical guidance for promoting listed companies to consciously improve their innovation ability and assisting our country to implement innovation-driven strategy through the stock market. Firstly, a mathematical model is established to theoretically research the influence mechanism of systemic risk shock and enterprise innovation ability on stock price volatility. And then taking the related data of China's A-share listed companies from 2013 to 2017 as sample, taking the continuous decline by more than 18% of China's CSI 300 index as the source of systemic risk shock, constructing the innovation ability index from three dimensions of innovation input, innovation output and innovation environment, the hierarchical regression analysis is used to empirically test the results of the theoretical model. The main research conclusions are as follows. Theoretically, the stock price volatility decreases with the increase of enterprise innovation ability, and increases with the enhancement of systemic risk shock. Enterprise innovation ability can weaken the impact of systemic risk shock on stock price volatility, thus enhancing the stock market stability. The empirical results based on the full sample show that the coefficients of systemic risk shock are significantly positive at 1% level, and the coefficients of enterprise innovation ability and the cross term of systemic risk shock and enterprise innovation ability are significantly negative at 1% level, which support the conclusions of the theoretical model. The empirical results based on the samples of SOEs and non-SOEs are similar to those based on the full sample. Systemic risk shock and enterprise innovation ability will have similar effects on the stock price volatility in SOEs and non-SOEs, and the only difference is that the effect of enterprise innovation ability on stock price volatility of non-SOEs is slightly less significant than that of SOEs, which also support the conclusions of theoretical model. The empirical results based on the samples of manufacturing and non-manufacturing enterprises show that the systemic risk shock will significantly increase the stock price volatility of manufacturing and non-manufacturing enterprises, but the influence of enterprise innovation ability on the two enterprises' stock price volatility has different significance levels. The basic characteristics of non-manufacturing enterprises' innovation ability and their internal relationship with firm performance and investor behavior make their innovation ability have no significant impact on stock price volatility.Base on the above-mentioned results, the following policy suggestions can be proposed. China's securities regulatory authorities should regulate market supervision behavior to reduce the frequency and impact of systemic risks, reform the listing system and delisting system to strengthen the "survival of the fittest" mechanism, optimize the innovation incentive mechanism to continuously improve the innovation ability of listed companies, and improve the information disclosure system to enhance investors' cognitive levels of systemic risk shock and enterprise innovation ability.

Key words: systemic risk shock, enterprise innovation ability, stock price volatility