In this paper, we introduce a new type of gain guided and index antiguided (GG-IAG) large mode area (LMA) fiber structure, basic theory and its important applications in fiber laser fields. We draw a conclusion that the side pump technology is the most appropriate scheme for GG-IAG LMA fiber after comprehensively analyzing the laser output characteristics and the thermal effect of the fiber under different pump conditions. The theoretical simulations of GG-IAG fiber side pump technology and the side pump experiment process are performed by the V groove technology, which is conducible to the experiment research in relevant fields. Finally, the suggestion of how to reduce the difference between the experimental results and the theoretical results is made and its relevant reason is also discussed.