Aiming at the uncertainty of online public opinion early warning and evaluation for food safety, a new online public opinion early warning and evaluation method for food safety was proposed. Firstly, a multi-level evaluation index system of public opinion early warning in the food safety network was established, and the warning grade and interval number grade of public opinion in the food safety network was put forward. The interval number weight of public opinion early warning evaluation index in the food safety network was determined by interval analytic hierarchy process. Then, combining with the interval number theory, an early warning and evaluation model of food safety network public opinion based on the interval analytic hierarchy process (IAHP) was constructed. Finally, the network public opinion early warning level of a food safety incident was evaluated with an evaluation example, which verified the rationality and effectiveness of the comprehensive evaluation model.