A biodegradable polyester composition based on a total weight of the biodegradable polyester composition, including a weight content of cyclopentanone which is 0.5 ppm-85 ppm is provided. The cyclopentanone is added into the composition and controlling the content of cyclopentanone in the composition within a range of 0.5 ppm-85 ppm to realize a lubrication degree of a film of biodegradable polyester during a blow molding process. When a velocity of film blowing is 176 Kg/h, a range of a film thickness is less than 0.2 μm and a relative deviation of the film thickness is less than 1%.