ROP (return-oriented programming) is a technique which is able to bypass the protection of the DEP (data execution prevention). The ROP can constitute a program that performs a specific function by searching for an appropriate assembly instruction fragment in the memory code area. Previous methods for automatic generation of ROP do not consider the limitation of the layout of ROP caused by the program memory requirement, which leads to poor practicability of ROP. In order to solve this problem, a new method for automatic fragmented layout of multi-module ROP based on symbolic execution was proposed. The ROP chain was divided into different modules on the basis of automatic ROP generation framework Q; the controllability of memory was dynamically analyzed by using symbolic execution tool S2E; the controllable memory areas for each ROP module was found, and the fragmented layout ROP was automatically constructed. Experiments show that, compared with the previous methods, the ROP chain generated by the proposed method can effectively reduce the requirements for the program memory controllability.