This paper analyzes the relationship between stock index and real economy from the perspective of long-term and short-term, stock and increment, and discusses the characteristics and existing problems of China's stock market barometer using the listed company data from 1995 to 2019.The results show that from the perspective of long-term equilibrium, China's stock index can reflect the trend of macro-economic development, but there is deviation in some stages, From the perspective of short-term volatility, the predictability of stock index is not strong, and the barometer effect is weak, not only weaker than developed countries such as the United States and Germany, but also weaker than BRICs such as Russia and India. In terms of stock, the failure to clear the low profit and loss-making listed companies in time affects the representativeness of stock index. Jn terms of increment, many high-quality enterprises choose to list overseas, which does not affect the representativeness of stock index. Using Wind index to reduce the influence of weight stocks on the total stock index, also chooses the blue chip stock index as the leading indicator, but these does not improve the prediction and warning effect of short-term fluctuation of stock index on macro-economy, and the barometer effect should not be improved significantly, which shows that the representativeness of stock index can't effectively reduce the disturbance brought by short-term sentiment and policy. Based on the empirical results, this paper suggests that the regulatory agencies should improve the delisting mechanism as soon as possible in terms of stock, speed up the reform of registration system in terms of increment, attract more excellent enterprises to be listed in domestic A-share market, and improve the quality of Listed Companies in two ways, so as to reflect the development of the real economy objectively. At the same time, the introduction of medium and long-term funds and the strengthening of institutional investors will help the short-term volatility of the stock market return to the economic fundamentals and promote its role as a barometer.