Heating transferring and flow field during TRC strip were analyzed by numerical simulation to understand effects of rolling velocity on temperature field and flow field under various conditions.Microstructure

morphology and constituent of the TRC magnesium alloy strip were analyzed by OM（optical microscopy）

SEM（scanning electron microscopy）.Based on simulated results and microstructure observation

central-line segregations in magnesium alloys strip was described.The results indicate that the rolling-casting speed has the great effect on heating transferring and flow field of melt in casting-rolling zone

and controlled the full solidification point of the strip.The sharp heating transferring can be observed in the melt along perpendicular to roller surface

resulting in the formation of columnar grain along opposite direction of heating transferring.Solute redistribution occurs in the solid-liquid interface of solidification front

so the Al

Zn element can be enriched in the soldering joint of top-bottom solidified shell

which are responsible for the formation of central-line segregation.