Investors' decisions are influenced by a wide variety of factors, including biological factors such as hormone levels in the body to psychological factors such as personality and past experiences. On the other hand, psychological factors such as self-confidence, fear of failure or risk-taking can affect personal investment decisions. With the interaction of these two types of factors, these effects can appear in a very complex and interesting way. Therefore, the purpose of this research is to investigate the impact of biological and psychological factors on investors' decisions with the moderating role of risk acceptance. This research in terms of practical purpose; In terms of nature, it is a descriptive-correlational method. Also, in terms of the method of data collection, it is survey type. The statistical population consists of 384 real and legal investors in Tehran who expressed their opinion through a researcher-made questionnaire. Structural equation modeling with SMART-PLS software was used to test the data. The findings show the positive and significant effect of cognitive biases on investors' decisions. Behavioral biases affect investors' decisions. Physiological factors influence investors' decisions. Genetic factors influence investors' decisions. Risk acceptance affects the impact of cognitive biases on investors' decisions.