Banking industry is one of most important sector in the economy of countries. Islamic banking and conventional banking has an active role in the financing, economy cooperation and economic development of countries. Todays, banking system face to some challenge and risks. Liquidity risk is one of challenge that treats the banks and if it be incontrollable and mismanagement, the result will be bankruptcy. The purpose of this research is comparative study of liquidity risk and management in Islamic banking and conventional banking by using index of finance ratios in two system. In this research data collected between 2012-2015 from balance letter of four Islamic bank in Iran and four conventional bank in Afghanistan. The result of research show that ratio of debit to assets, ratio of facilities to assets and ratio of facilities to deposits in elected Islamic banks in Iran are more than Afghanistan conventional banks. Surpass of this ratios are marks of more liquidity risk in Iranian Islamic banks. Ratio of capital to assets, ratio of cash to entire assets in elected Iranian Islamic banks are lower than this ratios in Afghanistan banks and this result shows that liquidity risk in Islamic banking is more than conventional banks.