To obtain the nanofibriled-cellulose(NFC) with uniform diameter and high aspect ratio, a chemical pretreatment is employed to remove the hemicellulose and the lignin of Larix gmelini with a subsequent ultrasonic treatment. The chemical characteristics, the crystalline type, the crystallinity and the morphological features of the as-prepared NFC are analyzed by the Fourier Transform Infrared Spectroscopy (FTIR), the X-Ray Diffraction (XRD) and the Scanning Electron Microscopy(SEM). It is shown that the obtained NFC has a uniform diameter of about 35nm and a high aspect ratio(>280). The crystalline type of the NFC is the cellulose I type, and the crystallinity reaches 62.8%, increased by 14.2% as compared with the raw material wood. Simultaneously, the high transparent NFC film and the ultralight flexible NFC foam are also fabricated by using the freeze drying technique.