Shrinkage reducing admixture (SRA) has been used to reduce the shrinkage of high strength concrete (HSC) by reducing the surface tension of capillary solution. Stress relaxation has an important role in evaluating the cracking potential of HSC at early age. However, investigations on the early-age stress relaxation and cracking potential of HSC mixed with SRA under restrained conditions were still lacking. Therefore, investigations on the effect of SRA on the early-age properties of HSC were conducted to guide the application of SRA on HSC. Investigations on the early-age stress relaxation and cracking potential of HSC with different SRA dosages (0%, 0.6%, 1.2%, and 1.8% by cement mass) by using restrained ring tests were conducted in the current research. Meanwhile, tests on the effect of SRA on the mechanical properties and free shrinkage of HSC were also carried out. The results indicated that the presence of SRA showed a slight decrease on the early-age mechanical properties of HSC. With the increase of SRA dosages, the reduction effect of SRA on the free shrinkage and steel strain had become more obvious, and the free shrinkage and steel strain of HSC at 28 d decreased by 58.46% and 44.64% when the SRA dosage was 1.8%, respectively. The maximum residual stress and stress rate of HSC were substantially decreased by the addition of SRA compared with the reference mixture. Moreover, the addition of 1.8% SRA could both reduce the 28-d maximum relaxed stress and the degree of stress relaxation by 77.58% and 45.28%, respectively. In addition, the cracking potential of HSC decreased with the increase of SRA dosages.