Based on the VP1 gene sequences, we constructed a time-scale evolutionary tree (Figure 2A). The phylogeny of the VP1 gene showed that GII.2 strains could be divided according to the type of RdRp gene. GII.P16-GII.2 could be subdivided into three clusters of strains in 2009–2010, 2010–2012, and 2012–2014. In addition, the phylogenetic divergence of the GII.P16-GII.2 strains might be wider than that of the GII.P2-GII.2 strains. The tree shows that the most recent common ancestor (MRCA) of the present GII.2 strains appeared in 1956 (mean ± 95% highest posterior densities [HPD]: 1945–1966). Subsequently, GII.P2-GII.2 virus strain emerged in 2000 (mean ± 95% HPD: 1998–2001). Moreover, the GII.P16-GII.2 strains detected in 2010–2012 diverged from a common ancestor of the GII.P2-GII.2 strains at 2002 (mean ± 95% HPD: 2001–2004). The GII.P16-GII.2 strains detected in 2009–2010 and 2012–2014 diverged at 2005 (mean ± 95% HPD: 2004–2007). The evolutionary rate of these VP1 genes was 2.987 × 10−3 substitutions/site/year (mean ± 95% HPD: 2.496–3.486 × 10−3 substitutions/site/year).