Based on the results, we compared the expression level of Notch1 in T-ALL with WT Notch1 or with Mut Notch1 group, definitive result indicated that the expression level of Notch1 was significant associated with Notch1 mutation in HD-N domain, significantly higher expression of Notch1 was detected in the T-ALL with Mut Notch1 group compared with WT Notch1 T-ALL group. The gene discussed is NOTCH1; the disease is acute lymphoblastic leukemia.