Freeze drying process is the drying method which preserves the original biological characteristics of products with high quality compared to other drying methods, providing high efficiency during usage. According to Ba TD , natto is known as a product extracted from soybeans fermented by Bacillus subtilis (natto) bacteria. It is used as a functional food to support stroke people, and used to prevent the disease. Therefore, the freezing drying process was used to study the impacts of factors such as: drying temperature, freezing water temperature, pressure, material thickness for preservation of the nutritional composition and biological characteristics of natto composition. Besides it determines the technological parameters (thickness of product: 11mm, the temperature of the product before freeze drying: -26°C; the pressure in the chamber sublimation: 0.008mmHg, sublimation chamber temperature: 38°C) during freeze drying process to increase the velocity of the drying process and shorten the drying time, thereby reducing the energy costs of drying.