Technological advances cause the business environment to experience rapid changes, especially in micro, small and medium enterprises (MSMEs). In the Indonesian economy, MSMEs are the largest business group and have proven to withstand the shocks of the economic crisis. This study aims to examine the role of system user training, personal technical skills, and organizational size in improving the performance of accounting information systems. The accounting information system in question is an application for managing the inventory of raw materials and calculating the cost of production based on a web developed by the researcher. MSME actors can use the application to manage inventory and determine the cost of production. This study uses a survey method with respondents of 34 employees in the production sector from 12 MSMEs in the Production Sector in Labuhanbatu Regency, North Sumatra Province, in 2022. Based on respondents' responses, obtained information that system user training is very important, organizational size is very appropriate, and personal technical ability and system performance accounting information is very high. The results showed that system user training and personal technical skills improved the performance of accounting information systems. Different results indicate that the organization's size does not affect the performance of accounting information systems.