The condenser of freeze-dryer is used to capture the water vapor from the drying chamber. A common problem of the condenser is that the frost is non-uniform and prone to "ice plugs". This paper studies the condenser of large food freeze-drying equipment, the structure of the condenser shell is changed from cylindrical to cone-cylinder, and the arrangement of condensing pipes in the condenser is changed to the non-uniform, condensing pipes is relatively sparse near the inlet, and it is relatively dense close to the outlet. The flow field in the condenser was analyzed by the finite element analysis method. The simulated result indicated that the vapor in the cone-cylinder shell is easy to form vortex, the streamline is uniform and long, and prolong the residence time of water vapor in the condenser, which is conducive to the uniform frosting and increase water vapor condensation rate. Introduction Freeze-drying orks by freezing the material and then reducing the surrounding pressure to allow the frozen water in the material to sublimate directly from the solid phase to the gas phase 1]. Widely used in medicine, food, biological products and preparation of nanomaterial. However, whether it is domestic equipment or the import of the freeze drying equipment, the common drawback is that the water vapor is too concentrated at the entrance of the condenser, easy to cause "ice plugs", lead to the low efficiency in water catching 2]. The performance of condenser is good or bad, which has a direct impact on the freeze drying effect or production efficiency, so it is necessary improve condenser structure to make it the frosting evenly and improve the water catching rate[3-4]. Especially for high energy consumption large-scale food freeze drying equipment, it is more important to solve this problem 5-6]. In this paper the condenser of large-scale freeze-drying equipment was modified by Dexi Wang's condenser. In order to improve the frosting uniformity and water catching rate 7]. Structure Design of Condenser The condenser is a low temperature condensate pump for pumping steam. 1 grams of water in the 133Pa vacuum degree, the volume of close to 1000L. If a working vacuum degree is 133Pa and the amount of sublimation is 60Kg per hour of the freeze drying machine, requirements of the vacuum system pumping capacity is equivalent to 6×107 L/h, need to have 28 pumps which pumping speed is 600L/S, this is virtually impossible to achieve[8]. Therefore, the pumping system on the freeze drying machine, in addition to the use of Steam-jet Pump, you must set the condenser in order to remove water vapor, to achieve the drying of the material. This study takes the shelf area is 100m 2 of the food freeze-drying equipment as an example to design the condenser. Condenser limit vacuum is 5Pa, no-load pumping air time is 0.5h, condensation pipes working temperature is -50 °C [9-10], the cooling time is not more than 1h. Through to the domestic and foreign large and medium-sized freeze drying machine investigation results show that the condensing area of condenser is related to the shelf area of freeze-drying chamber. And the area ratio is (3 ~ 4): 1, So 6th International Conference on Mechatronics, Computer and Education Informationization (MCEI 2016) Copyright © 2016, the Authors. Published by Atlantis Press. This is an open access article under the CC BY-NC license (http://creativecommons.org/licenses/by-nc/4.0/). Advances in Intelligent Systems Research, volume 130