PM2.5 samples were collected from five different cooking activities, namely, meat roasting, cafeteria frying, fish roasting, snack-street boiling, and cafeteria boiling in Ya’an, China. Their chemical compositions were investigated. The PM2.5 concentrations in the cooking samples were 2.5–9.6 times higher than those in the corresponding backgrounds. Meat roasting produced the highest amount of PM2.5. In general, charbroilings emitted more PM2.5 than the other cooking activities because of the characteristics of cooking method and fuel type. High organic carbon (OC) contents (N53% of PM2.5) and OC/EC ratios (N54) in meat roasting and cafeteria frying samples suggest that oils and high-fat raw materials significantly affect the PM2.5 and OC emissions. However, the cooking activity was proved to be a minor source for elemental carbon (EC) with its low contents in all of the samples. High ion compositions in PM2.5 and WSOC/OC ratios in the snack-street boiling and cafeteria boiling samples represent that water-based cooking emitted more water-soluble species. Considering that high OC/EC ratios were measured in the oil-based cooking samples and most secondary organic aerosols (SOAs) are water soluble, it is more reasonable to estimate SOA with WSOC/OC ratio in populated urban areas. We found that the formation of SOA is significant when the WSOC/OC ratio is larger than 0.40. Principal component analysis (PCA) with the quantified metals identified four contributors to the samples, including coal combustion and non-licensed business activities, soil dust, charcoal burning, and stainless steel utensils, and explained 73% of the total variance. The high emissions of PM2.5 and toxic components from the cooking activities suggest that food safety control and environmental standard establishment should be strengthened in small and medium-sized cities in China.