Previously we showed that aldehyde dehydrogenase 1A1 (ALDH1A1) is a new mediator for resistance of DLBCL to CHOP and a facility predictor of clinical prognosis. In the present study, knockdown and inhibitor of ALDH1A1 were applied to identify the role of ALDH1A1 in Raji cells. CCK-8 and clone formation assay were applied to determine the CHOP sensitivity and clone formation ability. Caspase colorimetric assay and Annexin V/FITC staining was performed to determine the degree of apoptosis. Western blot analysis was used to detect the NF-κB/STAT3 signaling proteins and apoptotic-associated proteins. Real-time quantitative PCR (RT-PCR) was used to identify the differential expression of ALDH1A1 between NHL patients and healthy donors. We demonstrated that inhibition of ALDH1A1 increased the sensitivity of Raji cells to CHOP, as indicated by increased cytotoxicity, reduced clonogenicity, activated caspase-3/-9, decreased NF-κB/STAT3 signaling and increased pro-apoptosis signaling, ad increased apoptosis rate. Moreover, we found high ALDH1A1 expression was associated with poor prognosis in NHL patients. Our data revealed the critical role of ALDH1A1 in NHL and provides a theoretical basis for the use of ALDH1A1 inhibitors in NHL patients.