In April 2020, the National Comprehensive Cancer Network (NCCN) released the first edition of the 2020 guidelines for cancer-associated venous thromboembolic disease (VTE). The guidelines mainly provide recommendations on how to prevent and treat VTE for cancer patients in inpatient and outpatient settings. Here, the authors focus on the comparison between the 2020 edition and the 2019 edition of NCCN guidelines, and interpret the updated risk assessment methods and prevention and treatment measures of VTE combined with clinical practical problems, so as to help the relevant medical workers to better understand and follow the guidelines.