From the perspective of behavioral finance theory, aiming at the phenomenon of “high cash holdings” and the frequent occurrence of illegal behaviors of listed companies in China,this paper makes an empirical analysis on all A share listed companies with illegal behaviors from 2012 to 2018, trying to reveal the influence mechanism of “representativeness heuristic” of company managers on cash holding decisions. The results show that the manager’s “representative heuristic” can significantly increase the level of cash holdings of listed companies in the next period. The promotion effect of the manager’s “representativeness heuristic” on the level of cash holdings can be realized through the increase of related party transactions.The adjustment mechanism test shows that under the influence of the external market environment, the manager’s “representativeness heuristic” has gradually weakened the promotion effect of the level of cash holdings.