Juice sac granulation is affected by pre-harvest factors and postharvest handling. Pre-harvest factors mainly include citrus type, irrigation frequency, delayed harvesting, climate, and rootstock (Al-Hosni et al., 2011; Kotsias, 2004). Several studies have found that lignin metabolism correlate well with the symptoms of juice sac granulation (Wu et al., 2014). She et al. (2009) showed that lignin content increased with the aggravation of citrus granulation. Meanwhile, the reducing of ascorbic acid (AsA), glutathione (GSH) and superoxide dismutase (SOD) will lead to the accumulation of reactive oxygen (H2O2), which will increased the activity of SOD, peroxidase (POD), and catalase (CAT). The increasing of POD and H2O2 further promotes lignin synthesis, which will cause juice sac granulation, indicating that increased lignin content is associated with citrus granulation.