Banana plants often experience pests and diseases, but many farmers have difficulty identifying the type of disease that attacks their plants. The lack of guidance from agricultural instructors also worsens this condition, which can lead to crop failure. Therefore, an artificial intelligence-based expert system is needed to help farmers identify and diagnose pests and diseases in banana plants. This study developed an expert system based on forward chaining and certainty factors to determine the type of disease and the level of certainty of the diagnosis. This system is designed to provide recommendations for appropriate actions to farmers to reduce the impact of pest and disease attacks.