Rod-shaped rutile TiO2 nanocrystals with various aspect ratios were prepared by a two-step wet-chemical method, and their photocatalytic performance for the reduction of uranyl ions under UV irradiation was investigated. Results show that there is an obvious difference between their specific activities based on equal surface area; rutile TiO2 nanorods with a moderate aspect ratio exhibited the best activity. Different occupation of {111} and {110} facets and a synergistic effect between them are proposed to explain the activity order.