Two aqueducts in 620m length were built 38 years ago. The flumes were U-shape and thin-wall structure in 10m span, which were simply supported on the reinforced concrete frames arranged in a row. After operated for 30 years, they were abandoned. Until 2009, with the increment of water supply of urban residents and landscapes of Zhengzhou city, they were considered to be reused. Therefore, the visual inspection on water-stops, seepage-proofing coating and concrete cracks of flume, the damages of supporting seats and reinforced concrete frames were conducted. The nondestructive testing for strength and carbonation of concrete, concrete cover and erosion of reinforcement were carried out. Based on the detected results, the serviceability and ultimate resistance of the aqueducts were evaluated in accordance with current Chinese design code. The measures were brought forward to strengthen their structures and repair their damages. The main results of these works are introduced in this paper, which can be used as reference for repairing the similar hydraulic concrete structures.