Electrospinning has got great development in recent years. In order to meet different needs, such as the research and applications, more and more materials have been developed for the technology, and solvents at the same time. Polymers are indispensable in electrospinning. The chapter deals with the introduction of the classification of polymeric materials in electrospinning, and their matched solvent systems. With the decrease of world oil resources and the rising of crude oil prices, the development of the traditional synthetic polymer industry has been restricted. At the same time, synthetic polymer materials are difficult to degrade, and the environmental pollution is becoming more and more serious. In addition, silk, spider dragline, and other natural polymer materials with special high strength performance also attracted researchers’ attention. There are a lot of natural polymers which can be processed by electrospinning technique in nature.