We investigate the probability distribution of the volatility return intervals τ for the Chinese stock market. We rescale both the probability distribution P q (τ ) and the volatility return intervals τ as P q (τ ) = 1/τ f (τ /τ ) to obtain a uniform scaling curve for different threshold value q. The scaling curve can be well fitted by the stretched exponential function f (x) ∼ e −αx γ , which suggests memory exists in τ . To demonstrate the memory effect, we investigate the conditional probability distribution P q (τ |τ 0 ), the mean conditional interval τ |τ 0 and the cumulative probability distribution of the cluster size of τ . The results show clear clustering effect. We further investigate the persistence probability distribution P ± (t) and find that P − (t) decays by a power law with the exponent far different from the value 0.5 for the random walk, which further confirms long memory exists in τ . The scaling and long memory effect of τ for the Chinese stock market are similar to those obtained from the United States and the Japanese financial markets.

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