Mid-infrared dispersive waves generated from supercontinuum generation are of great significance for gas sensing, environmental monitoring, and molecular spectroscopy. But the conversion efficiency of mid-infrared dispersive waves is degraded at longer wavelengths, which limits the application of mid-infrared dispersive waves. Here, we present a genetic algorithm (GA) which is modified by using a simulated binary crossover method and non-uniform mutation process. The modified genetic algorithm (MGA) optimizes the central wavelength, peak power and time duration of the pump to generate high-efficiency dispersive waves at around 3 µm. The conversion efficiency of mid-infrared dispersive waves is increased from 1.5% to 2.29%. These results are useful for gas sensing and environmental monitoring.