The work aims to provide a new way for the secondary utilization of waste spruce wood packaging. Waste spruce wood packaging was used as carbon source. Then, spruce carbon dots (S-CDs) were derived from carbon source by the hydrothermal method (180 ℃, 10 h) and applied to detection of formaldehyde. High-resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM) X-ray diffraction (XRD) and other instruments were used to investigate the morphology, crystallinity, chemical composition and optical properties of the S-CDs. In brief, S-CDs were spheroid with an average particle size of 3.49 nm, and the quantum yield was 0.45%. The surface contained C—O, C=O, N—H and other groups, which could be evenly dispersed in water. S-CDs were fluorescent blue excited at 365 nm. In addition, ratio fluorescence method was used to apply S-CDs in detection of formaldehyde. S-CDs showed a good response to formaldehyde. In the range of 0-1 mmol/L, the values of F427/F490 showed a good linear relationship with formaldehyde concentration (R2=0.968). The detection limit (LOD) was 0.045 mmol/L. Waste spruce wood packaging can be used as a single carbon source to prepare S-CDs which can be used for formaldehyde detection, thus realizing the secondary utilization and functionalization of waste spruce wood packaging.