Abstract: Double inner and outer latticed shell string-structure is a new type of space structure. Based on the local analysis method and the nodal equilibrium equation, the shape determination problem of a single plane double inner and outer beam string-structure is discussed, and then a simplified calculation method for the initial prestress of a ribbed latticed shell string-structure is proposed. Numerical algorithm is introduced and some suggestions for improvement are put forward and the parameter selection of calculation processing is discussed. Two examples are investigated by the above two methods and the calculation results are compared. The results confirm the feasibility of the above method. Finally, the process for the initial prestress design of a double inner and outer latticed shell string-structure is presented.