With advances in modern agricultural parks, the rural energy structure has undergone profound change, leading to the emergence of an agricultural energy internet. This integrated system combines agricultural energy utilization, the information internet, and agricultural production. Accordingly, this study proposes a regulation flexibility assessment approach and optimal aggregation strategy of greenhouse loads (GHLs) for modern agricultural parks. First, taking into account the operational characteristics of typical GHLs, refined load demand models for lighting, humidification, and temperature-controlled loads are established. Secondly, the recursive least squares method-based parameter identification method is designed to accurately determine key GHL model parameters. Finally, based on the regulation flexibility of quantitatively evaluated GHLs, GHLs are optimally aggregated into multiple flexible aggregators considering minimal operational cost and greenhouse environmental constraints. The results indicate that the proposed regulation flexibility assessment approach and optimal aggregation strategy of GHLs can alleviate the peak regulation pressure on power grids by flexibly shifting the load demands of GHLs.