The double cone rotary vacuum dryer is a drying equipment which integrates mixing and vacuum drying. The process of vacuum drying is to place the dried material in a sealed cylinder, and heat the dried material continuously while vacuumizing with the vacuum system, so that the moisture inside the material diffuses to the surface through the pressure difference or concentration difference. The water molecules (or other non condensable gases) get enough kinetic energy on the surface of the material, and diffuse to the low pressure of the vacuum chamber after overcoming the mutual attraction between the molecules The space is pumped away by a vacuum pump and separated from the solid. Therefore, the double cone rotary vacuum dryer has the following characteristics: (1) in the process of vacuum drying, the pressure in the cylinder is always lower than the atmospheric pressure, the gas molecular number is small, the density is low, and the oxygen content is low, so it can dry the medicine which is easy to oxidize and reduce the chances of material contamination. (2) Since the temperature of the wet fraction is directly proportional to the steam pressure in the vaporization process, the moisture content in the material can be vaporized at low temperature during vacuum drying to achieve low-temperature drying, which is especially suitable for the pharmaceutical production of heat sensitive materials. (3) Vacuum drying can eliminate the surface hardening phenomenon easily produced by atmospheric pressure hot air drying. This is because of the large pressure difference between the inside and the surface of vacuum drying materials. Under the effect of pressure gradient, the moisture will move to the surface quickly, and there will be no surface hardening. (4) Because of the small temperature gradient between the inside and outside of the material during vacuum drying, the moisture can be moved and collected by itself due to the reverse osmosis, which can effectively overcome the dispersion phenomenon caused by hot air drying.