Objective：Cysteine，a key component in the one-carbon metabolism，is of great importance in methylation. Many epidemiologic studies have assessed the association between cysteine and risk of cancer，but results are inconsistent. The objective of our meta-analysis is was to assess the association between plasma cysteine and cancer risk. Methods：Comprehensive searches were performed on PubMed and Embase databases up to November 1，2017 to identify relevant studies. Eight separate studies containing 11 comparisons were included in the meta-analysis. Relative risk（RR）and their corresponding 95% confidence intervals（95% CIs）were used to estimate the strength of relationship between cysteine and cancer risk. Results：The pooled RR of cancer risk for the highest versus lowest categories of blood cysteine level was 0.72（95%CI：0.62~0.83）with no significant heterogeneity observed（P=0.052，I2=45.1%）. Dose-response analysis showed that when plasma cysteine concentration was higher than 275 μmol/L，the higher cysteine level，the lower risk of cancer. Conclusion：Generally，our results indicated that higher concenteation of cysteine may decrease the risk of cancer.