The invention discloses a preparation method for a green cake, wherein the preparation method comprises the following steps: selecting glutinous rice and rice harvested in current year, adding purified water with the amount five times that of the glutinous rice and the rice, soaking, then taking out, air-drying and grinding into rice flour; putting folium artemisiae argyi into the soaked liquid, soaking, draining, then fumigating, taking out the folium artemisiae argyi, carrying out reduced pressure drying, and crushing; stirring and kneading the glutinous rice flour, the rice flour, the folium artemisiae argyi powder, fat pork, edible vegetable oil, cooking liquor, granulated sugar, a color retention agent and cooking liquor according to the ratio into a green rice flour dough; and carrying out mold inversion, cooking, cooling, packaging and sterilizing to obtain the finished product. Effective nutrients of the folium artemisiae argyi are fully retained, a case that a green juice is oxidized to be discolored in the green cake preparing process after the folium artemisiae argyi is crushed and wall-broken is avoided, and thus the prepared green cake is guaranteed to be more transparent and brighter, beautiful in appearance, and higher in nutritional value; the folium artemisiae argyi after crushing is added into the green cake, so that the content of crude fibers in the green cake is significantly increased, and the green cake tastes better, can be helpful for absorption of intestines and stomach, and has wide market prospects.