The invention discloses a method for preparing 1,1-difluoroethylene by cracking of 1,1,1-difluoro-1-chloroethane. The method includes steps of uniformly mounting inner metal components with catalysis effect in a cracking tube made of an inert material according to the filling quantity that the surface area of the inner metal components in each cubic meter of cracking tube is 100-500 square meters; placing the cracking tube into an electric heating furnace, controlling the temperature of the cracking tube within the range of 500-580 DEG C, leading 1,1,1-difluoro-1-chloroethane and retaining the same in a reaction section of the cracking tube for 20-400 seconds; quenching reaction products at an outlet of the cracking tube to below 100 DEG C through a water cooler, absorbing acid gas such as hydrogen chloride therein through a secondary washing absorption tower and a primary alkali cleaning absorption tower, freezing and drying to obtain cracked products. The method has the advantages that crack reaction temperature is low, conversion rate of raw materials is high, reaction selectivity is good, the service life of the cracking tube is long, and the method is applicable to industrial production.