A tetrahydropyridine compound represented by the following formula I, a stereoisomer thereof or a pharmaceutically acceptable salt thereof: wherein, n is 1, 2 or 3; R 1 is C1-C6 alkyl or C1-C6 haloalkyl; R 2 is hydrogen or C1-C6 alkyl; R 3 is hydrogen, C1-C6 alkyl, C1-C6 alkoxy, -OH or halogen; L is C3-C7 cycloalkyl, aryl, heteroaryl or null, wherein at least one H of C3-C7 cycloalkyl, aryl or heteroaryl may be substituted with halogen, C1-C6 alkyl, C1-C6 haloalkyl, - NR A R B or -OH; D is C=C, C3-C7 cycloalkyl, aryl, heteroaryl or null, wherein at least one H of C3-C7 cycloalkyl, aryl or heteroaryl may be substituted with halogen, C1-C6 alkyl, C1-C6 haloalkyl, - NR A R B or -OH; E is C=C, C3-C7 cycloalkyl, aryl, heteroaryl or null, wherein at least one H of C3-C7 cycloalkyl, aryl or heteroaryl may be substituted with halogen, C1-C6 alkyl, C1-C6 haloalkyl, - NR A R B or -OH; G is C1-C6 alkyl, C3-C7 cycloalkyl, 4-6 membered heterocycloalkyl, aryl or heteroaryl, wherein at least one H of C1-C6 alkyl may be substituted with halogen, -NR A R B, -OH or -ORc, at least one H of C3-C7 cycloalkyl or 4-6 membered heterocycloalkyl may be substituted with C1-C6 alkyl, C1-C6 alkyl-NR A R B, C1-C6 hydroxyalkyl, C1-C6 haloalkyl, C1-C6 alkoxy, C1-C6 alkyl-OR C, -NR A R B, -OH, -(C=O)-C1-C6 alkyl or -S(=O) 2 -C1-C6 alkyl, at least one H of aryl or heteroaryl may be substituted with C1-C6 alkyl, C1-C6 hydroxyalkyl, C1-C6 alkyl-NR A R B, halogen, nitro, cyano, -NR A R B, -OH, -OR C, -S(=O) 2 -C1-C6 alkyl, -S(=O) 2 -NR A R B or -N-S(=O) 2 -C1-C6 alkyl; R A and R B are each independently hydrogen or C1-C6 alkyl, or R A and R B may be linked together to form 4-6 membered ring, wherein the 4-6 membered ring may have O or S atom and at least one H of the 4-6 membered ring may be substituted with halogen, -OH or C1-C6 hydroxy alkyl; R C is C1-C6 alkyl, C1-C6 hydroxyalkyl, -(C=O)-NR D R E or -S(=O) 2 -C1-C6 alkyl; and R D and R E are each independently hydrogen or C1-C6 alkyl. n is 1, 2 or 3; R 1 is C1-C6 alkyl or C1-C6 haloalkyl; R 2 is hydrogen or C1-C6 alkyl; R 3 is hydrogen, C1-C6 alkyl, C1-C6 alkoxy, -OH or halogen; L is C3-C7 cycloalkyl, aryl, heteroaryl or null, wherein at least one H of C3-C7 cycloalkyl, aryl or heteroaryl may be substituted with halogen, C1-C6 alkyl, C1-C6 haloalkyl, - NR A R B or -OH; D is C=C, C3-C7 cycloalkyl, aryl, heteroaryl or null, wherein at least one H of C3-C7 cycloalkyl, aryl or heteroaryl may be substituted with halogen, C1-C6 alkyl, C1-C6 haloalkyl, - NR A R B or -OH; E is C=C, C3-C7 cycloalkyl, aryl, heteroaryl or null, wherein at least one H of C3-C7 cycloalkyl, aryl or heteroaryl may be substituted with halogen, C1-C6 alkyl, C1-C6 haloalkyl, - NR A R B or -OH; G is C1-C6 alkyl, C3-C7 cycloalkyl, 4-6 membered heterocycloalkyl, aryl or heteroaryl, wherein at least one H of C1-C6 alkyl may be substituted with halogen, -NR A R B, -OH or -ORc, at least one H of C3-C7 cycloalkyl or 4-6 membered heterocycloalkyl may be substituted with C1-C6 alkyl, C1-C6 alkyl-NR A R B, C1-C6 hydroxyalkyl, C1-C6 haloalkyl, C1-C6 alkoxy, C1-C6 alkyl-OR C, -NR A R B, -OH, -(C=O)-C1-C6 alkyl or -S(=O) 2 -C1-C6 alkyl, at least one H of aryl or heteroaryl may be substituted with C1-C6 alkyl, C1-C6 hydroxyalkyl, C1-C6 alkyl-NR A R B, halogen, nitro, cyano, -NR A R B, -OH, -OR C, -S(=O) 2 -C1-C6 alkyl, -S(=O) 2 -NR A R B or -N-S(=O) 2 -C1-C6 alkyl; R A and R B are each independently hydrogen or C1-C6 alkyl, or R A and R B may be linked together to form 4-6 membered ring, wherein the 4-6 membered ring may have O or S atom and at least one H of the 4-6 membered ring may be substituted with halogen, -OH or C1-C6 hydroxy alkyl; R C is C1-C6 alkyl, C1-C6 hydroxyalkyl, -(C=O)-NR D R E or -S(=O) 2 -C1-C6 alkyl; and R D and R E are each independently hydrogen or C1-C6 alkyl.