Both climate change and intensive human activities are thought to have contributed to the impairment of atmospheric visibility in Beijing. But the detailed processes involved and relative roles of human activities and climate change have not been quantified. Optical extinction of aerosols, the inverse of meteorological visibility is especially sensitive to fine particles <1.0mum. These submicron particles are considered more hazardous than larger ones in terms of cardiovascular and respiratory diseases. Here we used the aerosol optical extinction (inverse of visibility) as the indicator of submicron particles pollution to estimate its inter-annual variability from 1980 to 2015. Our results indicated that optical extinction experienced two different periods: a weakly increasing stage (1980-2005) and a rapidly increasing stage (2005-2015). We attributed the variations of optical extinction to the joint effects of human activities and climate change. Over the past 36years, human activities played a leading role in the increase of optical extinction, with a positive contribution of 0.077km(-1)/10y. While under the effects of climate change, optical extinction firstly decreased by 0.035km(-1)/10y until 2005 and then increased by 0.087km(-1)/10y. Detailed analysis revealed that the abrupt change (around 2005) of optical extinction resulted from the trend reversals of climate change. We found since 2005 the decreasing trend by 0.58m.s(-1)/10y in wind speed, the growing trend at 8.69%/10y in relative humidity and the declining trend by 2.72hPa/10y in atmospheric pressure have caused the rapid increase of optical extinction. In brief, the higher load of fine particles <1.0mum in Beijing in recent decades could be associated with both human activities and climate change. Particularly after 2005, the adverse climate change aggravated the situation of submicron particles pollution.