The invention discloses special ecological board decoration base paper and a preparation method thereof. The special ecological board decoration base paper comprises paper pulp, composite fillers andmulti-component retention agents, the paper pulp comprises whitened broadleaf wood sulfite pulp, whitened coniferous wood sulfate pulp, whitened broadleaf wood chemi-mechanical pulp and waste stuff, the composite fillers comprise modified nano-titanium dioxide, kaolin and talcum powder, and the multi-component retention agents comprise cationic polyacrylamide, silica solution and bentonite. By theaid of a staged filling technique, at a first stage, titanium dioxide is modified, and the modified titanium dioxide is added into a hydrapulper in the pulping process. At a second stage, the composite fillers such as the titanium dioxide, the kaolin and the talcum powder are dispersed by a high-speed dispersion machine, and the dispersed composite fillers are added into an approaching system. The filling quantity of the decoration base paper reaches 50% or more, and the ash content of the decoration base paper reaches 40% or more. The special ecological board decoration base paper has the advantages of high ash content, good covering performance and strength, sun resistance, environmental protection and the like and has a wide market prospect.