The mechanisms of organocatalyzed [2 + 2] reactions between α,β‐unsaturated aldehydes and nitroolefins with various substituents were explored using the density functional theory M05‐2X method. The calculations indicate that all 14 reactions we studied proceed through a stepwise mechanism and most of them are predicted to be feasible both kinetically and thermodynamically. The feasibility of the catalyzed reactions is mainly attributed to that the formation of dienamines could significantly increase the highest occupied molecular orbital (HOMO) energy of α,β‐unsaturated aldehydes, while the substituents have less influence. Also, the H‐bonding interactions between the catalysts and nitroolefins play a key role in the regioselectivity, and the stronger H‐bond favors the 3,4‐reactivity. Besides, the chemoselectivity is also discussed.