Root canal therapy is the preferred method to cure pulposis and periapical disease,and it is crucial to accurately determine the working length for successful root canal treatment.At present,measuring root canal length with Root ZX is an accurate method most applied.This article expounds the clinical application of Root ZX and influential factors in accuracy of measuring with Root ZX.The result shows that Root ZX can accurately determine the root canal length,which improves the effect of root canal therapy,its clinical application should be widespread.