The invention relates to a formaldehyde elimination agent and a preparation method thereof as well as an adhesive, a wooden product and an artificial board. The formaldehyde elimination agent comprises the following ingredients in parts by weight: 64-92.9 parts of pure water, 5-20 parts of urea, 2-15 parts of hydrazide compound and 0.1-1 part of an anionic surfactant. The formaldehyde elimination agent can be added into the adhesive and can be also sprayed on the wooden product and the artificial board. The formaldehyde elimination agent has the benefits as follows: on the basis of reaction between urea and formaldehyde, the hydrazide compound is added, so that the technical effect of no reverse reaction after reaction is realized; since the anionic surfactant is added, the reaction between effective ingredients in the product and formaldehyde in the artificial board is reinforced; the pH of the formaldehyde elimination agent is 7-9, the color of the wood material is not changed after the formaldehyde elimination agent is sprayed on the wood material with a light color, and the contents of formaldehyde in the adhesive, the artificial board and the wooden product reach the national compulsorily-executed health standard level.