The invention discloses a simulation biodegradation method of synthetic base drilling fluid and drill cuttings. The simulation biodegradation method comprises the following steps of adding 4-5kg simulation drill cuttings to 1300-1400ml synthetic base drilling fluid for mixing, adding 4-5kg topsoil, adding 2.5kg prepared organic matter, and adding 1.5-2.5g fertilizer, ventilating regularly, keeping the temperature at 20 DEG C, watering and mixing regularly, monitoring the temperature and the relative humidity everyday, and measuring a TPH (Total Petroleum Hydrocarbons) value by infrared spectrophotometry. If the TPH value is less than 1%, the synthetic base drilling fluid and the drill cuttings are biodegraded. After the synthetic base drilling fluid and the drill cuttings are degraded by the method, the aromatic content of a synthetic base solution is less than 1%, the environment cannot be damaged, and the biodegraded synthetic base drilling fluid and the drill cuttings can be used for soil cultivating.