The present invention discloses a high-flow lightweight insulating concrete and preparation method thereof. The high-flow lightweight insulating concrete includes cement, water, admixture and environmental friendly additives, wherein the mass ratio of the cement, admixture, environmental friendly additive and water is (15-25):(60-75):(0.5-1.5):(8-12). The present invention provides a high-flow lightweight insulating concrete and preparation method thereof, using effective gel in the construction debris as raw material. The renewable environmentally friendly active materials are prepared from the construction debris and have the characteristic of high-flow, which are suitable for the cast-in-place construction of the non-load-bearing wall. The construction process has advantages of simple, reliable, lightweight, high strength and cost-effective. And the non-load-bearing wall has the advantages of sound insulation, thermal insulation, is environmental friendly and durable.