This invention relates to a water-based flexible fake-proof printing ink, which is prepared from the following raw materials: 55-85 portions of natural orange oil resin, 5-35 portions of fake-proof material, 3-5 portions of assistant and 5-10 portions of diluting agent. The advantages of this invention are: 1. High efficiency and energy conservation. Due to the characteristic of flexible printing,to print the same amount the ink used in this invention is only 1/4-1/5 that of gravure printing, while the sale price is 1.4-1.5 times of the gravure printing products. 2. Environmentally friendshipand non-polluted. Since the printing ink in this invention is water-based and benzene-free, it can be diluted with distilled water and is environmentally friendly without any harm to human bodies. 3.Easy to wash. Since the printing ink in this invention is water soluble, the printing equipment can be directly washed with clear water after usage, and the operation is easy and rapid.