There is a large stock and serious pollution of electrolytic manganese residue and municipal solid waste incineration bottom ash in our country, and it is urgent to develop economically and technically feasible resource utilization technologies. Electrolytic manganese residue and municipal solid waste incineration bottom ash were used to prepare a road base material (RBM), and the chemical composition, mechanical properties, durability, leaching characteristics, hydration products, and pore structure of RBM with different Ca/Si ratios (mass ratio) were studied. The hydration products and microstructure of RBM were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TG), scanning electron microscope-energy dispersive spectrometer (SEM-EDX), and mercury intrusion porosimetry methods. The leaching characteristics of RBM were studied by leaching test. The results show that when the Ca/Si ratio is 0.8, the mechanical properties and pore structure of RBM are optimal, and the unconfined compressive strength (UCS) reaches 9.06 MPa after curing for 7 d, which meets the Class I standard of cement soil road base in China. The 28 d UCS of RBM after 9 freezing-thawing cycles and drying-wetting cycles is 11.63 and 9.90 MPa, respectively. The main hydration products in RBM are CaAl2Si2O8·4H2O, 3CaO·Al2O3(C3A), 2CaO·SiO2(C2S), and CaMnSi4O8. The strength and durability of RBM are improved by the interlacing of hydration products. The leaching concentrations of heavy metals and ammonia nitrogen in RBM meet the Chinese groundwater standard. This study can save the cost of road base materials while realizing the large-scale utilization of electrolytic manganese residue and municipal solid waste incineration bottom ash.