In China, Brucea javanica oil emulsion injection (BJOEI) has been used as adjuvant therapy to treat cancer for many years. Many systematic reviews (SRs) or meta-analyses (MAs) were published to evaluate its efficacy and safety. Nevertheless, uneven quality made it difficult to reach a consensus and there has been no specific review to integrate the evidence of BJOEI for cancer at present. Therefore, a comprehensive evidence map is needed to guide clinicians.We, for the first time, conducted an overview to assess the SRs/MAs of BJOEI, and provided a comprehensive evidence map to guide clinicians. Besides, this study provided a promising direction for future research to promote the generation of advanced evidence.An overview of SRs or MAs.The pre-defined search strategies were applied to 8 databases. Suitable SRs/MAs were included according to the inclusion and exclusion criteria. Methodological quality, reporting quality, and risk of bias were assessed. An evidence map was conducted to show the situation of clinical evidence.27 SRs/MAs in 7 cancer types were included in this overview. The main problems of SRs/MAs were concentrated on the following aspects: without registration or protocol, lacking gray literature retrieval and a list of excluded studies, incomplete description in the literature retrieval strategy or the methods of merging results, the bias of each synthetic result, less exploration in heterogeneity or publication bias, deficiencies in assessing evidence quality and less description in conflict, funding or access to relevant information. Based on the rules of GRADE, the evidence quality of 154 items in 27 SRs/MAs was defined as moderate quality (103 items), low-quality (44 items), and very low-quality (7 items). Especially, risk of bias (154 items), imprecision (27 items), inconsistency (20 items), and publication bias (9 items) were the main downgrading factors.BJOEI may be a promising adjuvant therapy for treating cancer, especially in the digestive system. However, high-quality SRs/MAs are expected to be carried out to improve the reliability of the above conclusion in the future.Copyright © 2022. Published by Elsevier GmbH.