Abstract: A new catalytic-spectrophotmetric method for determination of formaldehyde in food has been setup. In this method nanogold is used as the catalyst，which catalyzes the reaction of formaldehyde and Fehling reagent，and its product, cuprous oxide (Cu2O) particles, shows a broad absorption peak between 400~900 nm. A spectrohpotometric methed is used to measure the Cu2O absorption value at 870 nm. Experimental conditions of the formaldehyde-Fehling reagent-nanogold catalytic reaction were optimized. In the proposed method， the measured formaldehyde content obeyed Beer's law in the range of 1.2~600.0 μg/mL， with a linear regression equation of ΔA_{870 nm}=0.0014C+0.0627， a correlation coefficient of 0.999 2 and a detection limit of 0.45 μg/mL. Owing to high sensitivity， good selectivity， low-cost reagents， fast and good accuracy， the method has been applied to the determination of formaldehyde in food samples with satisfactory result.