Ring rolling is an advanced plastic forming technique which is used to manufacture precise seamless rings. Rolling ratio is regarded as a decisive parameter for the ring rolling process because it decides the blank dimension, reflects the ring deformation degree and influences the forming results. However, its importance for the ring rolling process is always neglected. In this paper, the effect of rolling ratio on the groove-section profile ring rolling is firstly investigated. The relationships between rolling ratio and blank dimension, rolling ratio and ring deformation degree are theoretically studied and a theoretical value range of rolling ratio is proposed. Then, with FE simulation, the influences of rolling ratio on the forming results are revealed. Based on comparison and experimental verification, a reasonable value range of rolling ratio is determined.