Understanding influencing factors on extubation in cardiac surgery patients has great importance. The aim of this study was to determine the relationship between demographic characteristics, medical and clinical variables as well as extubation time in this patients, in Cardiovascular Center. This research is a casual-comparative study, conducted on 210 adult patients underwent cardiac surgery, in 2018, in Tehran. Study samples were selected by convenience sampling method. The data collection tool was a researcher-made observation checklist that included four sections on patients' demographic characteristics, high risk factors related to the disease, patients' clinical condition in ICU, and clinical variables during surgery. The required data was collected. Study subjects were categorized into two study groups of more than 6 hours mechanical ventilation group and less or equal to 6 hours mechanical ventilation group based on their mechanical ventilation time. Using multivariate analysis test,the factors affecting endotracheal tube extubation were determined. IBM SPSS Statistics software version 21 was used for statistical analysis. Study subjects were 210 post-cardiac surgery patients including 142 males and 68 females with median age of 55. Findings indicated that age, sedation and duration of pulmonary circulation had a significant influence on extubation time in post-cardiac surgery patients. Findings indicated that age, sedation and duration of pulmonary circulation has impact on the process of extubation. Implementation of a precise discontinuation program from mechanical ventilation with considering these factors, are recommended in order to prevent long-term mechanical ventilation as well as reducing days of admission to ICU.