The synthesis of TS-1 zeolite with controllable crystal sizes has been successfully scaled up-by using the suspension of nanosized S-1 as seed in a TPABr-template hydrothermal system. Even under poor stirring condition, the suspended seeds can be easily dispersed in the mixture of zeolite precursor. Therefore the synthesis shows a very good reproducibility when scaled up from 2 L to 500 L, and the crystal size of TS-1 zeolite can be exactly controlled and changed in a wide range by only changing seed amount. Using this TS-1 zeolite through large-scale synthesis as material, the catalyst was prepared by modification and used in propylene epoxidation. The yield of propylene oxide based on H2O2 and propylene reaches 96.5% and 64.3%, respectively, which is superior to that of nanosized TS-1. Though the TS-1 samples synthesized with dried nanosized S-1 seed are similar to the samples synthesized with suspended seeds on the lab scale, the synthesis process using dried seeds shows a low reproducibility on the large scale. This research also implies the low cost and high energy efficiency of the production of TS-1 by using suspended seeds in large-scale process. (C) 2016 Elsevier B.V. All rights reserved.