The detailed kinetic mechanism of the C2H4 + NH2 reaction, an important reaction in both combustion and atmospheric chemistry, is first theoretically reported for a wide range of conditions (T = 250 - 2000 K & P = 1 - 76,000 Torr). The accurate composite electronic structure method W1U was used to explore the potential energy surface (PES) on which the temperature-and pressure-dependent kinetic behaviors of the title reaction were characterized using the complementary deterministic and stochastic Master Equation/Rice-Ramsperger-Kassel-Marcus (ME/RRKM) rate models. Corrections of the hindered internal rotation (HIR) treatment and quantum tunneling effect were included in the calculations. It is revealed that the title reaction can proceed via addition and H-abstraction channels leading to four different products (i.e., three addition products: CH2=CH-NH2 + H (P1), CH3CH-NH + H (P2), CH2 =NH + CH3 (P3) and one H-abstraction product: C2H3 + NH3 (P4)). The addition pathway is found favorable at low temperatures and high pressures: e.g., it dominates at temperatures lower than 650 K and 1250 K at P = 1 and 76 000 Torr, respectively. The computed rate constants are in good accordance with literature values; thus, the kinetic parameters, together with the thermodynamic data of the species involved, can be used confidently for modeling/simulation of nitrogen-related applications in atmospheric and combustion conditions. (C) 2019 The Combustion Institute. Published by Elsevier Inc. All rights reserved.