Abstract: Newly placed reinforced concrete structures during construction generally are supported by formwork, which transfers concrete deadweight and live loads to the placed RC floors. This temporarily load-carrying structure which consists of early-stage concrete structures and formwork is time-dependent. Its form, material property and space location all continuously vary with construction progress. In the analysis of the time-dependent structure, spacing uniformity and unchanged position of shores in upper and down level are generally assumed, but in practice there is formwork which is not consistent with that of shores in upper and down layers. This results in redistribution of construction loads between early-stage concrete slabs and shores. For analyzing the effect of weakened shoring layer on load distribution of reinforced concrete structures during construction, one simplified method is proposed, and verified by the results of engineering measurement. It is found that construction load carried by the slab above the weakened shoring layer is increased, and the construction load on the slab below the weakened shoring layer is decreased. The measurements for one high-rise concrete building during construction, indicate that the load carried by the slab above the weakened shoring layer is increased by about 4.3 percent, and the load carried by the slab below the weakened shoring layer is decreased by about 3.9 percent. Therefore, weakened shoring layer should be avoided to reduce the risk of reinforced concrete structures during construction.