Combustion and NO emission characteristics of a fuel blend comprising liquefied petroleum gas (LPG) and dimethyl ether (DME) were investigated using counterflow diffusion flames. Visible light photos, Schlieren photos, OH planar laser-induced fluorescence (PLIF) images, and maximum NO emissions were examined. The temperature, fuel-consumption rate, species mole fraction, species-production rate, and emission index of NO (EINO) were examined by numerical simulation. The experimental and numerical results showed that DME has a wider reaction zone, higher peak temperature, and greater reaction rate than butane. Although the overall LPG/DME mixture characteristics ranged between those of butane and DME, they were closer to those of butane. When the LPG contained propane, the mixture characteristics closely resembled those of DME because of their similar physical and chemical characteristics. The maximum NO concentrations decreased when the DME concentration increased. Owing to the higher fuel-consumption rate of DME, the EINO decreased almost linearly with the increase in the DME content.