Abstract: Carcinogenicity evaluation is an important field of pesticide risk assessment. However, the criteria and evidences for carcinogen classification vary from country to country. In this review, the carcinogen classification systems and principles currently used by International Agency for Research on Cancer (IARC), United States Environmental Protection Agency (USEPA) and European Union (EU) were summarized, and the characteristics and differences of them were analyzed. The IARC classification was based on the hazard level without reviewing the quantitative risk characteristics considered by other institutions. The mechanism of carcinogenesis was one of the important evidences for classification, but the associcated approaches adopted by various institutions were generally under processing. Taking glyphosate as an example, this review explained the complexity of carcinogenic evaluation due to differences in classification and evaluation methods, as well as differences in evidence collection and analysis. The purpose of this review is to provide reference for the establishment of pesticide carcinogen evaluation system and promotion related international communication in China.