Coagulant used for performing solid-liquid separation on waste drilling fluid in clean production and preparation method thereof

The invention discloses coagulant used for performing solid-liquid separation on waste drilling fluid in clean production and a preparation method thereof. The coagulant is prepared from, by mass, 10-45% of positive ion inorganic salt, 5-45% of oxidizing agents, 1-5% of catalyst, 1-10% of flocculating agents and the balance of water. The preparation method includes the steps that the balance of water and 10-45% of positive ion inorganic salt are sequentially added into a tank and stirred, after the added positive ion inorganic salt is completely dissolved into the water, 5-45% of oxidizing agents and 1-5% of catalyst are added and stirred for 2 or more hours, and finally, 1-10% of flocculating agents are added and stirred evenly. The coagulant can well achieve solid-liquid separation of the waste drilling fluid, meets the construction requirement for petroleum drilling clean production, all the components are low in price, and the preparation cost of the coagulant is effectively lowered; the preparation method is simple, on-site preparation is facilitated, and operability is high.