The invention discloses a method for preparing tussah moth oil, which comprises the following steps: manually dividing tussah moths which are the raw materials for industrial production of oophagous trichogrammae into male tussah moths and female tussah moths; respectively removing the wings; after using an egg wringing machine to break the bellies of the female tussah moths (the egg granules arenot broken), adding water the mass-to-volume ratio of which is 1:2 to immerse the processed female tussah moths, stirring the mixture, then passing the obtained product through a sieve, wherein the aperture of the sieve pore of the sieve is 3*3mm so that the egg granules can pass through the sieve pores and other parts of the tussah moths have larger volume so as to be left in the sieve; collecting the residues of the female tussah moths the eggs of which are removed; after using the egg wringing machine to smash the male tussah moths, collecting the residues of the male tussah moths; and respectively adopting the methods of cold soaking, ultrasound, reflux and supercritical carbon dioxide extraction to extract the collected male and female tussah moths to obtain a light yellow oily matter, i.e. the female or male tussah moth oil rich in bioactive substances. The method furthest utilizes the tussah moth residues to extract the tussah moth oil under the condition of not breaking the eggs of the tussah moths. The extracted tussah moth oil can be used as the by product for producing the oophagous trichogrammae. The method has simple process and low cost, and makes waste profitable.