The Common Public Radio Interface (CPRI) used in mobile fronthaul has low spectrum efficiency. In this paper, we propose to use Delta-Sigma Modulation (DSM) technology as a new fronthaul interface. In addition, to solve the problem of high computational complexity in the parameter searching of high-order stable Delta-Sigma modulator, Genetic Algorithm (GA) is used to search and optimize the structural parameters of the fourth-order Delta-Sigma modulator. The simulation results under the optimized structural parameters are compared with those under the original structural parameters. Under the condition of 1 bit quantization, the Delta-Sigma modulator with optimized parameters increases the transmission capacity of the system while the average Error Vector Magnitude (EVM) decreases from 0.031 to 0.028. In the case of 2 bit quantization, the average EVM decreases from 0.013 to 0.011.