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Severe haze in Beijing during February of 2020, corresponding to the pandemics of Covid-19, was ascribed to residential coal combustion, which is always air lean or of oxygen deficiency, for household heating in the rural areas around Beijing. In this study, a drop-tube furnace combustion system was employed, where five types of representative coal were burned under the conditions of three respective temperatures and an oxygen-deficient combustion condition to simulate different residential coal combustion regimes. The on-line number concentration distribution of particulate matters in flue gas emitted was obtained. By size-segregated particulate matters of PM 1 , PM 2.5 and PM 10 collected in a three-stage sampler during various coal burning, the mass of organic carbon (OC) and elemental carbon (EC) and optical properties of light-absorbing organic carbonaceous aerosol were measured extensively. The results indicated that high temperature encouraged the formation of sub-micron and ultra-micron particles. It was found that coal types had a great impact on the formation of EC aerosols, that is, the mass of EC decreased with increasing geological maturity. Besides, the formation of EC was also affected by temperature, that is, the lower the temperature was, the more EC components were generated. The optical properties of the aerosol particle extracted by methanol from PM 1 , PM 2.5 , and PM 10 were measured and explored. The high values of absorption Ångström exponent (AAE) and mass absorption efficiency at the wavelength of 365 nm (MAE 365) indicated the high wavelength-dependence characteristics and strong light absorbing abilities of brown carbon (BrC) from residential coal burning. AAE values from 1200 °C combustion emissions was observed to be diminishing with increasing fixed carbon to volatile matter ratio (FC/VM) and decreasing OC/(OC + EC). In addition, MAE 365 values from low-temperature combustion were higher. These findings help us better understand the role that household coal burning plays in global BrC emission and its harm on the environment and human health. Unlabelled Image • Emissions from insufficient coal combustion of different coal types and different temperatures were explored. • Formation of particulate matters was reduced under lower temperature. • Formation of elementary carbonaceous aerosols was sensitive to temperatures and coal types. • Brown carbon emissions from low-temperature insufficient coal combustion were more wavelength-dependent and light-absorbing. [ABSTRACT FROM AUTHOR]