A multicenter,open,prospective randomized controlled trial;11 study center in China; Plan to enroll 328 patients（ Power Analysis and Sample Size ）.Comparing FOLFIRI with mFOLFOX6,Superiority design.Investigate difference PFS,ORR,R0 resection rate,OS ,QoL and Safety from two regimens Stratification factors : Analyzing patients recurrence within 6-12months,and 12-18months .Obtain definite chemotherapy regimen shift opportunity for patients recurrence/metastasis after adjuvant chemotherapy.

Inclusion Criteria:

18-75 years，male or female Colorectal adenocarcinoma Accepting more than 4 cycles oxaplatin based adjuvant chemotherapy after radical operation Reccurrence in 6-18 months after adjuvant chemotherapy At least one assessable lesions No intestinal obstruction ECOG 0-1 Estimated survival≥ 3 months CBC：WBC>4×109/L，PLT>80×109/L，Hb>90g/L， Liver function：ALT or AST < 2× normal maximum value， T-bile<1.5× normal maximum value without hepatic metastatic， ALT or AST < 5× normal maximum value， T-bile<1.5× normal maximum value with hepatic metastatic Cr<1.8mg/dl Signed informed consent

Exclusion Criteria:

Locally resectable lesions Grade 2-4 oxaliplatin induced neurotoxicity Arrhythmias，coronary heart disease，or congestive heart failure（NYHA≥grade 2） requiring treatment Poorly controlled hypertension HIV infected or active HBV or HCV infected Active serious infection Cachexia or organ function decompensation Multiple primary carcinoma except carcinoma in situ of skin and cervix Participate in other clinical studies at the same time Serious heart or brain disease Drug abuse or other serious psychosocial diseases Suspected trial drug allergy Other factors affecting patient safety and compliance Pregnant or lactating women，or fertility without adequate contraceptive measures