3G service in Taiwan is in operation since June 2006. The wider bandwidth of wireless communication has realized many bandwidth-consuming application services, such as Multimedia Messaging Services (MMS). For the past 10 years, the Short Message Services (SMS) was a great tool in communication. However, SMS is only capable of transferring simple text, and thus is limited in terms of usage and application services. The application of MMS will definitely be widely accepted as the underlying 3G platform is being quickly deployed. In order to allow various applications to easily and quickly take advantages of MMS, this thesis focuses on the development of a MMS API. For software developers, to use the API in the development of MMS application service, a strong solid knowledge of the MMS operation is no longer a requirement. This thesis also uses a surveillance system as the demo example to illustrate that the proposed MMS API is a workable product.