In recent years, nanocellulose from a wide range of sources has attracted extensive attention. Nanocellulose is mainly divided into three categories: nanofibrillated cellulose (NFC), nanocellulose crystals (NCC), bacterial nanocellulose (BNC), which can be obtained by physical method, chemical method, biological method. Nanocellulose is an ideal nanomaterial in many fields due to its biodegradability and other properties. This paper is divided into two parts, focusing on the application and challenges of NFC and NCC in the food field and the application and challenges of BNC in the food field.