The shrinkage property of reactive powder concrete(RPC) can be improved by mixing coarse aggregate. 10 RPC normal concrete(NC) composite beams, 1 NC beam and 2 improved RPC specimens were designed on the basis of optimizing the mixture proportion. The shrinkage strain of RPC NC composite beam at mid span section and the shrinkage stress of longitudinal steel bars in the bottom of beams including steam curing process were investigated by using vibrating wire extensometer and stress meter. The results show that the total shrinkage strain of improved RPC material is 650×10-6660×10-6. All the influencing factors including the ratio of longitudinal reinforcement, height of RPC, concrete grade of NC, etc. have great effects on the shrinkage of composite beam at mid span section, which is compared with the shrinkage of NC beam. The stress of longitudinal reinforcement was 4063MPa in the bottom of RPC NC composite beams. The stress of longitudinal reinforcement is about 40 MPa in the bottom of NC beam. The results show that the shrinkage of improved RPC material is only 37% of normal RPC. It is indicated that the incorporation of gravel can greatly reduce the shrinkage of RPC and reduce the cost simultaneously. And this will promote the application of RPC in engineering.