The invention discloses a microcapsule suspending agent preapred from carbosulfan, chlorpyrifos and abamectin by compounding, and a preparation method thereof. The microcapsule suspending agent mainly comprises 5-20% of carbosulfan, 5-20% of chlorpyrifos, 0.1-5% of abamectin, 5-15% of solvent, 2-25% of capsule wall materials, 3-8% of emulsifier, 0.1-0.4% of thickener, 3-5% of antifreezing agent, 0.01-0.5% of corrosion remover, 0.1-1% of defoamer and the balance of water. By adopting the preparation, the effective components are coated with a capsule wall to form a microcapsule of an environment-friendly and low-public hazard slow-release pesticide suspending in water by adopting an interfacial polymerization method and a coating method. The compound preparation has a broad insecticidal spectrum, has good prevention and treatment effects on soil insects such as stem borers, grubs, cutworms, root-knot nematodes, bradysia odoriphaga and the like, and over-ground insects such as phylloxera, plutella xylostella and the like on crops such as corns, peanuts, vegetables, fruit trees and the like, and is long in lasting period, and the service efficiency of the effective components of the pesticide is improved.