Disclosure level in interim financial reporting is important for information users to make business decisions. This has received much attention from the information users. The article is aimed at determining the factors of financial ratios, which impact on the disclosure level in interim financial reporting. The authors use the ordinary least squares to test. The sample consists of 418 VN100 over a 6-year period from 2014 to 2019. The results show that there are four factors that positively impact on the disclosure level in interim financial reporting: Enterprise size (SIZE); Liquidity (LIQI); Sales growth (GROW) and Profitability (ROE). The article proposes some policy recommendations to contribute to improving disclosure level in interim financial reporting. Accordingly, State Securities Commission of Vietnam should strengthen the regular inspection of VN100's disclosure level in interim financial reporting and also should enforce strict sanctions or may consider delisting in cases of listed enterprises with incomplete disclosure. The managers of VN100 need to raise the sense of responsibility of information providers to ensure adequate information in interim financial reporting. Investors should also pay attention to the financial ratios of VN100 such as firm size, return-on-equity, liquidity, and sales growth to get useful information and ensure sound business decisions.