The Mg-3Y (wt%) alloy sheet was fabricated by pre-extrusion and subsequent single-pass large strain hot rolling process. The influences of different twinning types on dynamic recrystallization (DRX) and grain structure evolution during large strain hot rolling were investigated. Results show that the alloy undergoes nearly complete DRX during pre-extrusion processing under a low extrusion ratio of 8:1. During subsequent large strain hot rolling processing, deformation twinning, especially the {101} compres-sion and {101}-{102} double twinning, plays an important role in plastic strain accommodation. Moreover, the compression twin and double twin assisted DRX occurs extensively within the grains, and the recrystallization region is extended from the twin interior towards non-twinned regions, greatly relieving the internal stress. Both of processes above promote the formability of the alloy during large strain hot rolling processing.