Objective To investigate the protective effect of levocarnitine on nutritional status and adverse reactions in patients with colorectal cancer during adjuvant chemotherapy. Methods Patients with colorectal cancer who received mFOLFOX6 chemotherapy in our department after surgery were randomly divided into the observation group (use levocarnitine) and the control group. Detection (T0), 4 cycles of chemotherapy before the chemotherapy (T1) and 8 cycles (T2) patients after nutrition index, index of blood, the evaluation of degree of bone marrow suppression and gastrointestinal toxicity and peripheral nerve toxicity, and analyzed. Results There was no significant difference in body mass index (BMI), peripheral blood hemoglobin (Hb), peripheral blood lymphocyte (PBL) and serum albumin (ALB) between the two groups at T0. The content of Hb and PBL in peripheral blood of T1 observation group was higher than that of control group, and the difference was statistically significant (P<0.05). The difference between BMI and ALB were not statistically significant (P>0.05). The difference between White blood cell (WBC) and platelet (PLT) was not statistically significant, and the gastrointestinal toxicity and peripheral neurotoxicity were not statistically significant. At T2, the contents of Hb, PBL and ALB in peripheral blood of patients in the observation group were higher than those in the control group, and the differences were statistically significant (P<0.05), while the differences in WBC in peripheral blood were statistically significant (P<0.05). The differences in gastrointestinal toxicity were statistically significant (P<0.05), while the differences in BMI, peripheral blood PLT content and neurotoxicity were not statistically significant (P>0.05). Conclusion Levocarnitine can better maintain the nutritional status of patients, alleviate the reduction of neutrophils, and reduce the gastrointestinal toxicity of patients during adjuvant chemotherapy after colorectal cancer surgery, which is helpful for the maintenance of treatment.