分离过程（英语：separation process）在化学与化学工程中被用于将一些物质的混合物转化为两个或多个不同的产物。被分离的产物常在化学性质或一些例如尺寸、晶体形状等的物理性质上有所改变。

除了一些少数特例外，几乎每种元素或化合物在自然情况下都以两种或更多成分的混合物形式存在。有时需要将它们分成单独化合物的形式。化学工程领域中的分离应用显得尤为重要。原油是一个好例子：原油是多种碳氢化合物的混合物并且其天然形式就很有价值。然而我们常需要纯化过的多种碳氢化物，例如天然气、汽油、柴油、喷气燃料、润滑油与沥青等。

In chemistry and chemical engineering, a separation process, or a separation technique, or simply a separation, is a method to achieve any mass transfer phenomenon that converts a mixture of substances into two or more distinct product mixtures (which may be referred to as fractions), at least one of which is enriched in one or more of the mixture's constituents. In some cases, a separation may fully divide the mixture into its pure constituents. Separations are carried out based on differences in chemical properties or physical properties such as size, shape, mass, density, or chemical affinity, between the constituents of a mixture. They are often classified according to the particular differences they use to achieve separation. Usually there is only physical movement and no substantial chemical modification. If no single difference can be used to accomplish a desired separation, multiple operations will often be performed in combination to achieve the desired end.