Abstract: For the problem of occurrence rate high of central longitudinal crack on tangsteel hot rolled plate,In order to effectively achieve the purpose of reducing occurrence rate of central longitudinal crack.This paper as relying on the 1 700 mm production line of Tangsteel hot rolling department,The influencing factors of central longitudinal crack for hot rolled plate low-carbon-low-sillicon-aluminium killed steel as SPHC were studyed and analysised by industrial test,numerical simulation and site investigation.The results showed that:There are many factors that affect center crack of SPHC slab,which are mainly reflected in the factors such as immersion depth,Mn/S,casting speed,mold taper,mold type,covering slag type and submersed nozzle type and other factors.After through the above measures to optimize the adjustment,The average incidence rate of central cracks eventually can be achieved that from the original 5.38% to the current less than 0.96%,in order to improve the effective protection for successfully produce high-quality steel products on the 1700 continuous casting production line.