Bio-based chemicals synthesis by lignin offers a promising pathway of bioenergy utilization to achieve the target of the Paris Agreement with < 2°C of climate warming temperature. Recently, numerous efforts have been conducted in lignin biorefinery including lignin extraction, separation, depolymerization and products separation, of which each subprocess has a profound effect on overall process. The right configuration and integration implementation of biorefinery subprocesses determines the ultimate efficiency and cost. This review provides an in-depth mechanism understanding on subprocesses aiming to giving an enlightenment on right configurations and integration implementation of subprocesses and early commercialization of lignin biorefinery. This review includes: 1) elucidation of lignin biosynthesis pathway, 2) dissection of mechanism of biorefinery subprocesses with intelligible graphical overviews and summary, 3) analysis of tech-economic viability from the view of market potential and each biorefinery subprocess, and 4) discussion of challenge and perspective with the emphasis on gene engineering and start-up time of lignin-based bioenergy popularization. Present-day results indicate more efforts should be performed toward the gene engineering regulation and integration implementation of subprocesses to promote early commercialization of lignin biorefinery considering that delayed use of bioenergy may reduce carbon emission mitigation capacity and increase global food risk.