In this paper, the characteristic of the plastic shrinkage cracking of the lightweight aggregate concrete (LWAC) was studied under the condition of prescribed quantity of cement and aggregate and was compared with that of the normal aggregate concrete (NC) with the same proportion of materials for the LWAC. The results suggested that the water evaporation quantity in the concrete became larger with the increase of w/c, and water evaporation velocity reached maximum value around two hours. When the water-cement ratio was low, the area of the plastic shrinkage cracking of LWAC was large and when w/c was 0.40, the area reached the maximum value and then became smaller with the increase of w/c.