Assessment of SO3 micro-thermal explosion pretreatment on wheat straw was conducted.
77.5% of lignin in wheat straw was removed after pretreatment.
Cellulose and hemicellulose were almost not to be degraded to form inhibitor.
The highest saccharification rate of the pretreated wheat straw was 89.3%.
Hydration of SO3 and esterification of lignin were the key factors of the process.