The expansion and micro-cracks of the mortar with composite mineral admixtures (fly ash, zeolite and slag) due to the alkali-silica reaction (ASR) are studied. Results show that composite mineral admixtures cannot absolutely diminish the ASR of mortar bars with the low-alkali cement and a highly reactive aggregate. But the expansion rate and the deleterious expansion of the mortar bar are mostly reduced with increasing composite mineral admixture. The influence of mineral admixtures on the fluidity of the paste and the strength of the mortar is also studied.