A vehicle air intake mechanism adapted to be connected to an air filter of a vehicle, characterized by: an air intake duct adapted to be connected to the air filter and having an inlet end portion that extends in a first horizontal direction and that defines an inlet end opening which opens in the first horizontal direction; and a flow-guiding member connected to said inlet end portion of said air intake duct and having an outer surrounding wall that defines a flow channel in fluid communication with said inlet end opening, said outer surrounding wall having first and second end portions (321 a, 321 b) that extend in the first horizontal direction and that define first and second axial ends (3211, 3212) of said outer surrounding wall respectively, said first end portion (321 a) of said outer surrounding wall surrounding said inlet end portion of said air intake duct, said first axial end of said outer surrounding wall defining a first end opening that is in fluid communication with said flow channel and that opens in a second horizontal direction opposite to the first horizontal direction for inducing environment air, said inlet end opening being disposed between and spaced apart from said first and second axial ends (3211, 3212) of said outer surrounding wall; wherein the flow-guiding member further has a sleeve wall and an interconnecting wall, said sleeve wall being surrounded by said outer surrounding wall and being sleeved on said inlet end portion of said air intake duct, said interconnecting wall being disposed between and interconnecting said outer surrounding wall and said sleeve wall; wherein said flow channel has a first half that is confined by said first end portion (321 a) of said outer surrounding wall and the inlet end portion of the air intake duct, and a second half that is confined by said second end portion (321 b) of said outer surrounding wall and the interconnecting wall, said second half having a variable vertical cross-sectional area along a horizontal direction perpendicular to the first horizontal direction, said variable vertical cross-sectional area having a maximum cross-sectional area which is located adjacent to the sleeve wall and that is less than the area of said first end opening; and wherein said maximum cross-sectional area of said variable vertical cross-sectional area is greater than the area of said inlet end opening. an air intake duct adapted to be connected to the air filter and having an inlet end portion that extends in a first horizontal direction and that defines an inlet end opening which opens in the first horizontal direction; and a flow-guiding member connected to said inlet end portion of said air intake duct and having an outer surrounding wall that defines a flow channel in fluid communication with said inlet end opening, said outer surrounding wall having first and second end portions (321 a, 321 b) that extend in the first horizontal direction and that define first and second axial ends (3211, 3212) of said outer surrounding wall respectively, said first end portion (321 a) of said outer surrounding wall surrounding said inlet end portion of said air intake duct, said first axial end of said outer surrounding wall defining a first end opening that is in fluid communication with said flow channel and that opens in a second horizontal direction opposite to the first horizontal direction for inducing environment air, said inlet end opening being disposed between and spaced apart from said first and second axial ends (3211, 3212) of said outer surrounding wall; wherein the flow-guiding member further has a sleeve wall and an interconnecting wall, said sleeve wall being surrounded by said outer surrounding wall and being sleeved on said inlet end portion of said air intake duct, said interconnecting wall being disposed between and interconnecting said outer surrounding wall and said sleeve wall; wherein said flow channel has a first half that is confined by said first end portion (321 a) of said outer surrounding wall and the inlet end portion of the air intake duct, and a second half that is confined by said second end portion (321 b) of said outer surrounding wall and the interconnecting wall, said second half having a variable vertical cross-sectional area along a horizontal direction perpendicular to the first horizontal direction, said variable vertical cross-sectional area having a maximum cross-sectional area which is located adjacent to the sleeve wall and that is less than the area of said first end opening; and wherein said maximum cross-sectional area of said variable vertical cross-sectional area is greater than the area of said inlet end opening.