In recent years， nano-silica has attracted extensive attention in the oil and gas industry due to its ultra-high specific surface area and pozzolanic reaction with cement. In this paper， the research status of nano-silica in cementing slurry is systematically reviewed with focus on the effects of nano-silica on the water loss and thickening time of cementing slurry， and on mechanical properties and microstructure of hardened cementing slurry as well. The effects of nano-silica on the performance of cementing slurry under high temperature is also summarized. The existing problems， challenges and future development direction of nano-silica application in cementing slurry are discussed so as to provide some suggestions and ideas for the development and application of nano-silica in the cementing field.