Revealed in this 2 - Spiro Nucleosides and their Derivatives useful for treating a subject infected by hepatitis C virus and dengue virus. It also discloses a method for preparing the compound.Claim 1: a compound or its Salt or stereoisomer or its metabolite or its deuteruro represented by the formula (1): (i), wherein R1 is selected from hydrogen - (a), (b) P (o) (OH) 2, c) - P (o) (OR 1 - (CH2) 3oC (alkyl) (OR) 2, d) - P (o) (OR (CH2) 1 - 3oC (OR) (alkyl) 2, (e) - P (o) (OR (1 - (CH2) or 3SC (alkyd) ILO 2, f))) - P (o) (OR (CH2) 1 - 3och2 (aryl) 2, (g) - P (o) (OR (CH2) 1 - 3sch2 (aryl) 2(H) * - P (o) (or1a) (nhchr1bc (OR) or1c A1a), where Hydrogen is (i), (ii) alkyl, aryl or cycloalkyl (iii) (iv), r1b is Hydrogen (i), (ii) - 6 (iii) C1 alkyl, cycloalkyl, IV or v) alcarilo ALK (heteroaryl) r1c) and is (i) ii) hydrogen, alkyl, cycloalkyl or alcarilo (iii) (iv), (i) - P (o) (NH (alcaril) (OR (CH2) 1 - 3SC (OR) (alkyl) - (j)), a dioxafosfinan 1,3,2 - 2 - k) - Oxide, a 4h benzo [d] [1,3,2] dioxafosfinin - 2 - Oxide,L *) - P (o) (or1c) ~ or ~ - When and where r1c defined previously, m) - P (o) (o) - O - P (o) (OH) 2, n) - P (o) (OH) (- O - P (o) Oh) - or - P (o) (OH) 2), or an acyl, p) a Rent C1 - 6 - Oxy acyl, and Q a) - C (o) - O - (ii) alkyl； R2 is selected from Hydrogen, fluoro a) b) c azido ciano), (d), (e) an alkyl Or C1 - 6 (f) and (g) A VINYL etinilo； (iii) to R3 is selected from Hydrogen, Methyl, (b))Ciano and (c)； (iv) and is selected from Hydrogen, fluoro (a) (b), (c) - (d) - or ~, when R1 is - P (o) (or1c) ~, where r1c defined previously, e) - or (acyl) - or (f), let C1 - 6 - Oxy acyl), (g) - or - C (o) - O - (alkyl) - NH2, NH (acyl) - (i), (j) - NH - C (o) - O - (k) azido alkyl, X is selected； (V) Held between (a) or (b), (c) - S -, - NH -, - CH2 - (d), (e) >； c = CH2,And (f) - NH - C (o) - or - alkyl； (VI) The Z ring is a Ring of four or five members selected among radical structures represented by formula (a) - (OR), where * represents the point of Uni
