The measurement of PM2.5 was conducted from 15th August to 17th September, 2015 in Shijiazhuang, China, covering the period of a ceremonial parade. The PM2.5 concentrations and the major chemical components were analyzed. The concentrations of PM2.5 was 26.5 µg m–3 during control, which were 57.0% and 51.1% lower compared to before and after control, respectively. The lowest concentrations of elements and water-soluble ions were also found during control with a decreasing tread of 31.1%–44.2%, and 57.1%–64.2%, respectively. Two typical pollution episodes characterized by significantly elevated PM2.5 concentration were found during no control due to the combination of no emission-reduction measures and unfavorable weather conditions. The mass percentage of secondary inorganic ions was larger during no control (38.1%–40.3%), pointing to the strong contribution of atmospheric chemical processes. The NO3–/SO42– ratios were 0.85, 0.94, and 0.85 before, during, and after control, respectively, and the elevated ratios during control indicate a greater proportion of the PM2.5 originated from vehicle exhaust. The WRF-CMAQ modeling system was also used to assess the effectively of emission reduction measures and weather conditions. The results indicated that the PM2.5 concentration increased by 21.6% and 32.1% if no emission-reduction measures were taken and weather conditions in 2014 were used.