Objective <p>The new sagittal sacral morphological parameters including Sacral-1 tilt (S1T) and Sacral-2 tilt (S2T) were independently measured without hip axis, which efficacy in predicting lumbar sagittal alignment was compared with pelvic incidence (PI) in this study.</p> Methods <p>The aforementioned parameters were retrospectively measured by the standing full-length spine X-rays of 388 asymptomatic individuals aged from 18-year to 35-year: S1T defined as the angle between sacral plate and S1-Co1; S2T defined as the angle between sacral plate and S2-Co1. Also sagittal spino-pelvic parameters containing pelvic incidence (PI), pelvic tilt (PT), sacral slope (SS), lumbar lordosis (LL), thoracolumbar kyphosis (TLK) and thoracic kyphosis (TK) were recorded. In addition, segmental lumbar sagittal alignment comprising proximal lumbar lordosis (PLL), distal lumbar lordosis (DLL), and the ratio of distal lumbar lordosis to lumbar lordosis (DLL/LL) was evaluated. The associations among S1T, S2T and lumbar lordosis, segmental lumbar alignment were analyzed.</p> Results <p>LL, PLL, and DLL were positively related to PI, however, negatively correlated with S1T and S2T. Of these, compared with PI, S1T and S2T showed stronger correlation with LL(<i>r</i> = -0.543, <i>r</i> = -0.559, vs. <i>r</i> = 0.528) and DLL(<i>r</i> = -0.279, <i>r</i> = -0.297, vs. <i>r</i> = 0.240). Conversely, compared with S1T and S2T, PI showed a stronger correlation with PLL (<i>r</i> = 0.454, vs. <i>r</i> = -0.436, <i>r</i> = -0.438). The correlations of PLL with S1T, S2T and PI was significantly stronger than those of DLL.</p> Conclusion <p>S1T, S2T and PI were significant predictors for lumbar sagittal alignment, of these, PI was obviously related to PLL while S1T and S2T were particularly associated with LL and DLL. S1T and S2T could represent lumbar lordosis without radiographic images of femoral head and may serve as supplementary indicators to PI for predicting lumbar lordosis alignment.</p>