The invention discloses durable three expansion source concrete expanding agent, which is characterized by comprising anhydrite, high-aluminum clinker, high calcium-sulfur-aluminum clinker, calcined magnesite and the like as the preparation raw materials according to a weight proportion, in addition, the raw materials are added with air entraining agent K12, siliceous dust, zeolite powder and water repellent sodium stearate. A preparation method comprises steps of crushing, common blending, blended powder grinding and external finished product blending. The expanding agent has low alkali content, has certain expansibility, and improves cracking resistance and impermeability of concrete. The expanding agent after being added into the concrete can remarkably improve compactness, impermeability, anti-scouring property and abrasion-resisting property of the concrete, reduces permeability and water absorption greatly so that the concrete has higher self-defending capability and environmental medium erosion resistance, improves sulphate erosion resistance and carbonizing resistance of the concrete greatly, is favorable for improving safety and durability of the reinforced concrete, and is suitable for various concretes.