Due to its unique character, Coiled tubing technology is widely used in various fields of marine oil and gas operations. But as the stiffness of coiled tubing is small, and the marine environment is complex, it is easy for the coiled tubing to destroy or cause an accident. Therefore we need to study axial load transfer characteristics of coiled tubing in the Marine riser to ensure safety and reliability of the operation. In this paper, through establishing the finite element model of coiled tubing down into of marine riser, axial load transfer law of unfixed boundary and fixed boundary coiled tubing was analyzed. Analysis results show that within fixed boundary condition, coiled tubing axial load transfer efficiency would be higher than that in unfixed boundary when the injection force is greater than the helical buckling critical load.Index Term -Pipe in pipe; Load transfer; Finite element analysis.