Abstract: The effect of natural zeolite on restraining alkali-silica reaction has been investigated through the tests of measuring the ion exchange capacity of natural zeolite with time, the hydration degree of natural zeolite and the influences of natural zeolite on alkali content in the pore solution. The results show that the ion exchange rate is of the highest at the first 10 minute, the ion exchange capacity reaches 80% of the total capacity in 2 hours and the exchange tends to equilibrium in about 2 days. In the case of cement being replaced by 30% of natural zeolite and the duration of hydration for 6 months, the hydration degree of natural zeolite is about 40%-50%. The ASR expansion is restrained by natural zeolite through reducing the water soluble alkali content and the effective alkali content. There is no disadvantage effect of the alkali in natural zeolite on restraining alkali-silica reaction, when the replacement level of cement by natural zeolite is more than a certain quantity.