【Objective】To investigate efficacy and toxicity of a new modified FOLFIRINOX regimen（mFOLFIRI? NOX）as first-line chemotherapy for the patients with metastatic pancreatic adenocarcinoma（MPC）.【Methods】20 patients with metastatic pancreatic adenocarcinoma（MPC）accepted mFOLFIRINOX arm（oxaliplatin 60 mg/m 2 ，irinotecan 150 mg/m 2 ，bolus of 5-FU 400 mg/m 2 ，continuous infusion of 5-FU 2 400 mg/m 2 ）first-line treatment and evaluated the curative effect and side effect after 3 cycles by imaging and laboratory at Sun Yat-sen Memorial Hospital from December 2012 to December 2016. The primary endpoint was overall survival（OS）. The second endpoint was response rate（ORR） and toxicity.【Results】Four patients were excluded according to exclusion criteria. A total of 16 patients were enrolled including 7 males and 9 females. The median age is 55 years（ranging from 43 to 67 years）. The median cycle of chemo? therapy was 4.5（3-15）. The ORR was 31.3% including 5 patients with partial response，9 patients with stable disease and 2 patients with progression disease. The median follow-up duration was 14.1（2.7-24.5）months. The median OS was 16.6 months（95%CI，11.36-21.84）. Overall survival rates at 6，12months were 80%and 55.6%，respectively. Three patients were presented grade 3-4 adverse events.【Conclusion】The new mFOLFIRINOX regimen improved survival of patients with MPC with tolerated toxicity as first line treatment.