Pledge is a conception that has plentiful meanings and on the different conditions it has different significances. Generally, the pledge has two types. The one is that the people promise for the effects of theriselve's behaviors. The other meaning is that the people promise to the third people and guarantees the effects of the third people. But as the contract for the pledge that we offen contact in the ture bussiness or normal activities, it has some traits that the normal contracts have not own and how the nature of the pledge contract embodys the special character is the vital thing for us to study the pledge contract. About the problem above, opinions and statements are so many and different. But that is why it is necessary to make sure and penetrate into the nature of the pledge contract.