A cytidine derivative dimer, having the following general formula, wherein: R1 is C 1 -C 10 alkyl, C 1 -C 10 substituted alkyl, -(CH 2) n -Ph, or substituted -(CH 2) n -Ph; in the -(CH 2) n -Ph, n=0, 1, 2, 3∼10, and Ph is phenyl; a carbon chain of the substituted alkyl is independently substituted by one, two, or three of halogen, cyano group, nitro group, amino group, hydroxyl group, or carboxyl group; and in the substituted -(CH 2) n -Ph, n=0, 1, 2, 3∼10, and a carbon chain or a phenyl ring of which is independently substituted by one, two, or three of halogen, cyano group, nitro group, amino group, hydroxyl group, or carboxyl group; R2 is C 1 -C 10 alkyl, C 1 -C 10 substituted alkyl, -(CH 2) n -Ph, or substituted -(CH 2) n -Ph; in the -(CH 2) n -Ph, n=0, 1, 2, 3∼10, and Ph is phenyl; a carbon chain of the substituted alkyl is independently substituted by one, two, or three of halogen, cyano group, nitro group, amino group, hydroxyl group, or carboxyl group; and in the substituted -(CH 2) n -Ph, n=0, 1, 2, 3∼10, and a carbon chain or a phenyl ring of which is independently substituted by one, two, or three of halogen, cyano group, nitro group, amino group, hydroxyl group, or carboxyl group; R3 is hydrogen, alkoxycarbonyl or substituted alkoxycarbonyl, wherein a substituent of the substituted alkoxycarbonyl is halogen, cyano group, nitro group, amino group, hydroxyl group, or carboxyl group; R4 is hydrogen, alkoxycarbonyl or substituted alkoxycarbonyl, wherein a substituent of the substituted alkoxycarbonyl is halogen, cyano group, nitro group, amino group, hydroxyl group, or carboxyl group; and R5 is -(CH 2) n -, n being from 1 to 15, or substituted -(CH 2) n - with a substituent on a carbon chain thereof, the substituent is phenyl group, substituted phenyl group, cyano group, nitro group, amino group, hydroxyl group, carboxyl group, or -(CH 2) n -X 1 -X 2 -; in the -(CH 2) n -X 1 -X 2 -, n=0, 1, 2, or 3, X 1 is O or S, and X 2 is -(CH 2) n -Ph, n being 0, 1, 2, or 3, or X 2 is pyrimidyl, pyranyl, imidazolyl, pyrazinyl, or pyridyl. R1 is C 1 -C 10 alkyl, C 1 -C 10 substituted alkyl, -(CH 2) n -Ph, or substituted -(CH 2) n -Ph; in the -(CH 2) n -Ph, n=0, 1, 2, 3∼10, and Ph is phenyl; a carbon chain of the substituted alkyl is independently substituted by one, two, or three of halogen, cyano group, nitro group, amino group, hydroxyl group, or carboxyl group; and in the substituted -(CH 2) n -Ph, n=0, 1, 2, 3∼10, and a carbon chain or a phenyl ring of which is independently substituted by one, two, or three of halogen, cyano group, nitro group, amino group, hydroxyl group, or carboxyl group; R2 is C 1 -C 10 alkyl, C 1 -C 10 substituted alkyl, -(CH 2) n -Ph, or substituted -(CH 2) n -Ph; in the -(CH 2) n -Ph, n=0, 1, 2, 3∼10, and Ph is phenyl; a carbon chain of the substituted alkyl is independently substituted by one, two, or three of halogen, cyano group, nitro group, amino group, hydroxyl group, or carboxyl group; and in the substituted -(CH 2) n -Ph, n=0, 1, 2, 3∼10, and a carbon chain or a phenyl ring of which is independently substituted by one, two, or three of halogen, cyano group, nitro group, amino group, hydroxyl group, or carboxyl group; R3 is hydrogen, alkoxycarbonyl or substituted alkoxycarbonyl, wherein a substituent of the substituted alkoxycarbonyl is halogen, cyano group, nitro group, amino group, hydroxyl group, or carboxyl group; R4 is hydrogen, alkoxycarbonyl or substituted alkoxycarbonyl, wherein a substituent of the substituted alkoxycarbonyl is halogen, cyano group, nitro group, amino group, hydroxyl group, or carboxyl group; and R5 is -(CH 2) n -, n being from 1 to 15, or substituted -(CH 2) n - with a substituent on a carbon chain thereof, the substituent is phenyl group, substituted phenyl group, cyano group, nitro group, amino group, hydroxyl group, carboxyl group, or -(CH 2) n -X 1 -X 2 -; in the -(CH 2) n -X 1 -X 2 -, n=0, 1, 2, or 3, X 1 is O or S, and X 2 is -(CH 2) n -Ph, n being 0, 1, 2, or 3, or X 2 is pyrimidyl, pyranyl, imidazolyl, pyrazinyl, or pyridyl.