Right of pledge plays an important role in economic society as one of the right of assurance.Pledge contract is an important element of establishment of pledge right,and its properties and forms makes an difference on which pledge right comes into force,but we have many misunderstandings about it because of some defects on Assurance Law of China,especially about its key element of establishment.So we will pay more attention to it and probe into properties and forms of pledge contract on the base of Assurance Law.