The invention discloses a simvastatin tablet and a preparation method thereof. The simvastatin tablet comprises an active ingredient simvastatin and pharmaceutical excipients, wherein the pharmaceutical excipients are spherical lactose, cross-linked sodium carboxymethyl cellulose, butylhydroxyanisole, hydroxypropyl methyl cellulose, silicon dioxide, magnesium stearate and film coating premix, which are added according to a specific mass ratio and process. The simvastatin and the pharmaceutical excipients are incompatible, and are prone to hydrolysis and oxidation, lactone bonds break to open loop to generate an active metabolite simvastatin hydroxy acid under the high-humidity condition, the intramolecular diene bond is subjected to a slow oxidative copolymerization reaction to generate a dimer or polymer under the high-temperature condition, and the preparation of a stable preparation is greatly difficult. In recent years, with the continuous disclosure of information, the difference between the quality standards of simvastatin tablets produced by different manufacturers is great, wherein the dissolution behavior difference is more significant, so that the situation that the simvastatin tablets have the same name but have different quality is very obvious. The prescription process determined by the study can continuously produce the simvastatin tablet at large scale, and the prepared simvastatin tablet has a good dissolution performance in various PH-value dissolution media, and keeps good stability in the long-term storage process.