3G applications have developed rapidly in some countries. The experience of operating 3G core applications from some operators is worth learning. This paper summarized five main principles based on describing the core applications of typical 3G operators: 1. Provide personalized services: provide practical services to meet the needs of customers in all aspects, act as customers’ personal assistant; 2. Provide personalized and customized services, according to the needs of different customers: According to the different characteristics of different customers, customize personalized services; 3. Provide integrated services: connect mobile phones with other tools, develop converged services; 4. Innovate services continuously: Combine with the original advantages of the companies, innovate services continuously, seek for the development of differentiation; 5. Expand the cooperation among the industrial chain, attract and develop customers: make multilateral cooperation, provide a variety of services and promote mutual development of the industry.