Traditional online broad learning system are unable to adapt to dynamic changes in data streams for concept drift data stream classification. To address this issue, this paper proposes an Adaptive Online Broad Learning System (AOBLS) classification algorithm that introduces an adaptive forgetting factor and concept drift detection mechanism. Additionally, this paper proposes a concept drift index to measure the degree of concept drift. By combining the concept drift index and forgetting factor, the model can adaptively adjust the size of the forgetting factor to better handle concept drift. Experimental results demonstrate that the proposed algorithm performs better than similar algorithms in terms of classification accuracy, stability, and concept drift adaptability.