An intake system of engine comprises an intake pipe (8), an air intake manifold (6), and an auxiliary intake assembly (4) disposed on the intake pipe (8) and located before the air intake manifold (6) of an engine. The auxiliary intake assembly (4) comprises an auxiliary air inlet passage, an auxiliary air outlet passage (21), and a central passage (39). Air enters through the auxiliary air inlet passage, comes out from the auxiliary air outlet passage (21) and enters the central passage (39), so as to be mixed with air from the intake pipe (8). The present invention further relates to an engine intake system, comprising an electronic booster (4″) located upstream of the air intake manifold (6) of an engine. An air flow enters from an air inlet (4241″), flows out from an air outlet (4242″), is mixed with air that flows through the intake pipe (8), and then is inhaled into a cylinder of the engine. The present invention further relates to a engines comprising the above intake systems. These intake systems and engines can effectively reduce discharge, reduce fuel consumption, improve engine efficiency, improve a low-speed torque feature of the engines, and improve a low temperature cold start effect of the engines.