Abstract: In order to improve the permeability resistance of concrete protective layer and avoid surface cracks, and then improve the durability of reinforced concrete, vacuum dewatering process was adopted in this research. The performance of vacuum dewatered concrete and its improvement mechanism were studied by macroscopic performance test and micro pore structure analysis. The test results show that: (1) The vacuum dewatering rate and performance of vacuum dewatered concrete can be improved by using lower initial water-binder ratio, less water consumption per unit and more than about 20% suitable sand ratio compared with non-vacuum dewatered concrete. (2) After vacuum dewatering, the increamental value of compressive strength of concrete after 28 d increases with the water-binder ratio; and the improvement value of concrete abrasion resistance strength after 72 h decreases with the increase of water-binder ratio. And the improvement effect of low water-binder ratio on abrasion resistance strength is particularly significant. (3) Compared with non-vacuum dewatered concrete, the dry shrinkage deformation of vacuum dewatered concrete decreases and the permeability resistance of vacuum dewatered concrete improves significantly. The results of pore structure analysis show that vacuum dewatering process mainly increases the volume content of pore size of 20~50 nm in concrete, and the total porosity, maximum pore size, critical pore size and average pore size of concrete decrease obviously. Vacuum dewatering process optimizes and refines concrete pore structure. Vacuum dewatering process can be used as an effective measure to improve the performance of reinforced concrete protective layer.