The invention provides a method for preparing a calcium-silicon-potassium-magnesium soil conditioner. The method comprises the following steps: A, preparing raw materials; B, grinding; C, calcining; D, water quenching; E, crushing; F, granulating; and G, drying. According to the preparation method, potassium-containing shale is utilized to prepare calcium-silicon-potassium fertilizer, so that potassium in the calcium-silicon-potassium fertilizer is sufficiently utilized as potassium fertilizer, and silicon oxide in the calcium-silicon-potassium fertilizer is sufficiently utilized to produce excellent silicon fertilizer; limestone and dolomite added into production are sufficiently utilized to produce calcium fertilizer and excellent soil conditioners; the raw materials are sufficiently utilized and converted into fertilizer, and the fertilizer cannot cause soil acidification, alkalization and hardening after being applied, the commodity quality and product quality of crops can be remarkably improved, and the crops have higher nutritional value.