This study aimed to determine the impact of liquidity risk on financial performance of Jordanian banks, where liquidity risk was measured by (Liquidity ratio, net working capital, cash and investment ratio to total deposits), and financial performance was also measured through the index (return on assets) and the modifying variable (bank size) measured through the natural logarithm of total assets was also added. To achieve the objectives of the study, the analytical quantitative approach was adopted. The study community consisted of all 13 commercial banks listed on the Amman Stock Exchange. All banks in the study community were selected as a study sample using the comprehensive survey method, and the statistical analysis program (SPSS) was used to test the study hypotheses. Based on the results of the statistical analysis, it was found that there was an impact of liquidity risk on financial performance measured by return on assets in Jordanian commercial banks listed on Amman Stock Exchange, and there was an impact for each of (current liquidity ratio, net working capital, cash and investment ratio to total deposits) on financial performance measured by return on assets in Jordanian commercial banks listed on Amman Stock Exchange. It was also found that the size of the bank contributes to modifying the effect of liquidity risk on financial performance measured by return on assets in Jordanian commercial banks listed on Amman Stock Exchange. The study concluded a set of recommendations, the most important of which are: commercial bank administrations should increase interest in exploiting their liquidity within acceptable risk limits to reach optimal ratios for financial performance by balancing the returns to be achieved with the potential risks of such expenses in a way that ensures the positive impact of liquidity risk on the financial performance of those banks.