China has abundant biomass equal to over four million tons of standard coal, which can directly substitute coal in residential energy system. The focus was to quantify performances of household biomass co-combustion by comparing energy efficiency, emission characteristics and economic value of biomass, coal and co-fuel in a typical coal-burning stove under space-heating and cooking phase to promote clean and cheap biomass energy in rural areas. The results indicated that energy efficiency of co-fuel was much higher than that of biomass in coal-fire stove with a value of 68.10% in heating phase and 54.50% in cooking phase. The gaseous pollutant of SO2, NO and NO2 emitted from co-combustion were reduced significantly compared with coal burning, and PM2.5 was decreased to a low concentration which was much lower than the limiting value (100mg/MJ) of Chinese standard. The emission reduction of SO2, NO, NO2 and PM2.5 was 22%, 67%, 88% and 18%, respectively, in heating phase, while the reduction emission was 11%, 64%, 63% and 33%, respectively, in cooking phase. The organic emissions of US-EPA priority PAHs with high carcinogenicity were also controlled well and the emission reduction of high-ring PAHs could reach 34% and 87% in heating and cooking phases. Compared with biomass in coal-fire stove, the emission of CO from co-fuel combustion was low with the reduction of 46% in heating phase and 61% in cooking phase. Moreover, the emission levels under heating phase were more stable than cooking phase due to relatively less artificial operations. The co-fuel was cheap, whose price on a unit energy basis was 0.039yuan/MJ and the price on a unit mass basis was only half of coal. The burner of co-fuel was popular coal-burning stove, avoiding purchasing expensive biomass stove and ensuring the expenditure for daily energy uses within the economic bearing capacity of low-income families. 