Recently, two derivatives of PVP named PVP-A and PVP-E were synthesized by our group and PVP-A was verified to have good inhibition performance by experiments. PVP-A and PVP-E were obtained by introducing a butyl ester group and a butyl ether group into PVP molecules, respectively. In this work, the inhibition process of hydrate growth at molecular level was simulated to explore the inhibition performance of PVP-A, PVP-E, and PVP and clarified their inhibition mechanism. Our simulation results show that PVP-A has the best inhibition performance among these selected KHIs which was in accordance with experiments. The binding interactions between inhibitors and liquid water molecules play a significant role in inhibition performance of KHIs. The strong binding effect could greatly disrupt the hydrogen-bond structure between the water molecules in the vicinity of hydrate nucleus surface and attract more water molecules to form hydrogen bond with KHIs rather than build hydrate clathrate on the surface of hydrate nucleus and therefore prevents the hydrate nucleus reaching the critical nuclear size for subsequent spontaneous growth. (C) 2017 Elsevier Ltd. All rights reserved.