The invention relates to a half artificially fed cabbage moth feed and a preparation method thereof. The feed is prepared by mixtures A, B and C, agar and distilled water, wherein the mixture A comprises casein, sucrose, malt meal and wild cabbage powder; the mixture B comprises cellulose, para hydroxybenzoic acid, potassium sorbate and Watkins salt; the mixture C comprises vitamin C, streptomycin sulphate, propyl gallate, vitamin B complex, edible vegetable oil, potassium hydroxide and formalin. The preparation method comprises the following steps: components of the mixture A, B and C are respectively put into a container; 5/6 of the distilled water and the agar powder are added into the container for heating and stirring to thawing; the mixture A is poured into the agar liquid and stirred until uniformity; the mixture B is added and stirred until uniformity; the rest distilled water is added, and the mixture C is added when the temperature is decreased to 70 DEG C, and then stirred until uniformity; the obtained product is filled into moth feeding cups; after the surface moisture is dried, the cups are put into a refrigerator for storage. The preparation method and the feed of the invention are scientific, simple, and easy to standardize propagation the cabbage moth indoors with large scale; the cabbage moth fed with the feed has high larva survival rate, orderly development and sound growth; and the descendants of the cabbage moth have high hatching rate.