Abstract: Objective To investigate the efficacy and safety of the cetuximab combined with chemotherapy for patients with metastasis from colorectal cancer whose K-Ras status were wild type and explore the factors that may affect the efficacy and prognosis. Methods Retrospectively collected the clinical data of 90 patients with metastasis from colorectal cancer whose K-Ras status were wild type. Cetuximab 400mg／m2 was intravenously given at first dose and maintenance at 250mg／m2 every week or 500mg／m2 every two weeks. Combined chemotherapy regimen included， irinotecanbased chemotherapy（FOLFIRI or XELIRI or irinotecan monotherapy）， oxaliplatinbased chemotherapy（FOLFOX or XELOX），other regimens， such as 5-FU／leucovorin or capecitabine monotherapy. The efficacy and safety of each line of chemotherapy was summarized and assessed， and the relationship between clinicopathology features， treatment characteristics and efficacy， explore the factors associated with prognosis were analyzed retrospectively. Results The median duration treatment of cetuximab was 16 weeks（6-44 weeks）. And in all patients the objective response rate（ORR） was 45.6％，and the disease control rate（DCR）was 87.8％. The DCR in first line treatment was 51.6％ better than in second line， whose was 40.0％， and the DCR in third line was 18.2％. The age， location of primary tumor， treatment time of cetuximab might affect the efficacy fo cetuximab plus chemotherapy. In the 90 patients， recurrent metastases were occurred in 82 cases（91.1％） and death in 60 cases（66.7％）. The median PFS（mPFS） was 7.8 months and median OS（mOS） was 22.5 months. In the first line treatment of cetuximab plus chemotherapy， mPFS was 91 months and mOS was 276 months. In second line treatment mPFS was 7.7 months and mOS was 14.5 month. in third line mPFS was 2.9 months and mOS was 6.7 months. Univariate survival analysis showed that the location of primary tumor，early tumor response and treatment time of cetuximab were related to PFS and OS of the patients， and the metastasis scope was related to the OS of patients. Using the Cox multivariate hazards model to analysis the clinicopathological factors， which showed that the location of primary tumor and early tumor response were the independent risk factors affecting the PFS of patients， the metastasis scope was the independent risk factor affecting the OS of patients. The most common adverse reaction related to cetuximab is acnelike rash， the side effects associated with chemotherapy mainly were diarrhea， nausea， vomiting， bone marrow suppression. After symptomatic treatment， patients can tolerate. Conclusion Cetuximab combined chemotherapy in each line treatment of patients with metastases from colorectal cancer can get great efficacy， and the adverse reactions can be tolerated. The location of primary tumor might be the predictors of the efficacy， and it is also associated with the prognosis of the patients. As ETS Shows that early tumor response could be one of the outcome indicators of mCRC.