New model descending style Rotary Evaporator to adapt Rotating Flask of big capacity and big calibration; it can increase evaporating area, to put it into water bath in decompression, over rotating over heating to diffuse effectively liquid to finish evaporation. It is used in consentration, drying, extraction, recycling. It is good device for big production. characteristics: main machine: introducing advanced transmission system, the structure is reasonable to endure long time in warranty. control-temperature: introducing abroad advanced converting-frequency control system, temperature control system to ensure exaction of rotary evaporator Water Bath: choosing imported stainless board to make it, vertically automatical lift. Sealing: choosing the latest PTFE material to make it by special craft to enhance Sealing, Non-corrosion, high wearing feature. main structure: to adapt quality duralumin and stainless material.