The invention discloses a zirconium-base amorphous alloy and a preparation method thereof. The composition of the zirconium-base amorphous alloy is represented by a formula below: (ZraM1-a)100-xOx, wherein a represents the ratio of the number of Zr atoms to the total number of Zr atoms and M atoms, and a ranges from 0.1 to 0.9; M is at least one selected from transitional elements and IA and IIA groups in the periodic table of elements; and x represents the number of oxygen atoms, and the plastic strain of the zirconium-base amorphous alloy varies from 0.5 to 20 percent according to the rangeof x. The invention also provides a method for preparing the zirconium-base amorphous alloy. In the invention, the plastic strain of the zirconium-base amorphous alloy is improved obviously by controlling the oxygen content of the materials of the alloy, a vacuum condition and hot melting time.