The invention discloses lightweight self-compacting concrete comprising the components of cement, limestone powder, calcined expanded clay, sintered shale ceramic sand, an air-entraining agent, a thickener, a viscosity regulator, a water-reducing agent, and water with a ratio of (450-550): (20-70): (750-900): (100-300): (1-30): (1-30): (0.1-2): (5-15): (170-210). The invention also discloses a preparation method of the concrete. The method has the advantages that: calcined expanded clay and sintered shale ceramic sand are adopted as aggregates, and the performance of the lightweight concrete is regulated by adding the air-entraining agent, the thickener, the viscosity regulator, and the water-reducing agent, such that various working performances satisfy the requirements of self-compacting concrete. The concrete has good anti-segregation performance, excellent pumping performance, self-compacting performance, and high strength. With the viscosity regulator, the production of the lightweight self-compacting concrete is more stable and efficient. Also, natural sand is not adopted as the aggregate, such that sand and gravel mining is not involved in the production, and environment-protection significance is provided.