The physin sterol is present in a large amount in the physalis seed oil, and the seed oil is extracted therefrom by microwave assisted method, and then saponified and extracted to obtain an acid sterol. The response surface method was used to optimize the extraction conditions of phytochemical sterol. The results showed that: under the condition of absolute ethanol as extractant, the liquid-to-liquid ratio was 11:1 mL/g, the extraction time was 7 min, the extraction temperature was 51 °C, the microwave power was 500 W, and the physalis was used. The yield of sterol was 1.771 mg / g. The original acid pulp seeds and ethanol microwave-assisted extraction of physalis seeds were scanned and observed by transmission electron microscopy. It can be seen that the phytoplasma seed cells have a large amount of fat particles on the surface and the particles are full; the microwave-assisted extraction of the physalis seed cell wall is completely broken. The cell membrane permeability is increased, and a large amount of seed oil is leached from the cells. The microwave-assisted method has a good effect on the extraction of phytochemicals.