The atmospheric ozonolysis mechanism of (E)-2-formylcinnamaldehyde is investigated at the CCSD(T)//M06-2X/6-311++ G(d,p) level of theory. The reaction starts with the formation of primary ozonides (POZs), which decompose to four primary products as phthaldialdehyde+CIs (Criegee intermediates, syn- and anti-FC-CI-1) and glyoxal+CIs (syn- and anti-FC-CI-2). The calculated rate coefficients are in reasonable agreement with the experimental values. In the atmosphere, for stabilized FC-CIs, syn-/anti-FC-CI-1 and anti-FC-CI-2 tend to react with water, forming alpha-hydroxyalkyl hydroperoxides, while syn-FC-CI-2 would most likely cyclize to a bicyclic compound. The produced multifunctional products might contribute substantially to the formation of secondary organic aerosols.