The invention discloses a bipolar interlayer veneer and a preparation method thereof, and belongs to the field of material veneer processing. The bipolar interlayer veneer comprises a nonpolar base layer, a bipolar intermediate layer and a surface polar decoration layer, wherein the nonpolar base layer is made of plastic or a wood-plastic composite material; the bipolar intermediate layer is madeof one of a non-woven fabric weaving material, a linen weaving material, a cotton fabric weaving material, a paper weaving material, a non-woven fabric non-weaving material, a linen non-weaving material, a cotton fabric non-weaving material and a paper non-weaving material coated or steeped with a thermoset adhesive; and the surface polar decoration layer is made of a polar wood decoration material or a polar paper decoration material. When the prepared bipolar intermediate layer is heated, plastic on the surface layer of the base material is fused to be fused with the nonpolar surface of theintermediate layer or penetrates into interspaces, the thermoset adhesive at the other side undergoes chemical reaction with the polar surface material, and by means of the bipolar intermediate layer,the base material is adhered to the surface layer decoration material.