Background There is tremendous interest in the development of liquid biopsy techniques, but the potential role of liquid biopsy for the early detection of cancer has not yet been elucidated. We aim to explore the performance of liquid biopsy in the early diagnosis of cancer. Methods A systematic review was conducted of liquid biopsy in cancer early detection. Meta-regression was carried out to explore the source of heterogeneity and publication bias was also evaluated. Results Overall, there were six types of biomarkers and 17 studies focusing on liquid biopsy in the early detection of cancer, 7 studies in ctDNA, 5 studies in cfDNA, 2 studies in CTC, and the other three studies used circulating nucleosome, microRNA, and multiple biomarkers, respectively. Pooled sensitivity and specificity of liquid biopsy in cancer early detection was 0.76 (95%CI:0.67-0.83) and 0.92 (95%CI:0.86-0.96) and the area under the SROC curve was 0.91 (95%CI:0.88-0.93). Conclusions The current evidence shows that liquid biopsy has relatively low sensitivity and high specificity in cancer early detection. Among all these biomarkers, cfDNA may have potentially promising value in cancer early detection, thereby supporting further study of cancer early detection. Study Registration The study is registered at PROSPERO (Identifier number: CRD42020137205).