Abstract: The correctness evaluation of seawater dissolved oxygen (SDO) is important for understanding the stability of marine ecosystem. SDO data is a non-linear time series and the visibility graph method turning the time series into graphs is a more effective way to analyze such data, but there is still the problems of considering simultaneously the time evolution of the data and the interaction between variables. To address the existing problems, this paper proposes an assisted evaluation method for SDO based on graph similarity matching. First, considering the influence of SST and salinity on SDO and the irreversibility of the data, the dissolved oxygen temperature salinity-transition probability (DOTS-TP) directed visibility graph method is proposed to realize the transformation from multivariate time series date to univariate transformation of DO graphs. Then, on the basis using the dissolved oxygen graph on the Gulf of Mexico as the evaluation reference, the multi-level information of the graph is synthesized and the subtree node global (SNG) graph similarity matching method is proposed, and the SNG evaluation index is calculated to achieve the auxiliary evaluation of dissolved oxygen in seawater. The experimental results show that the DOTS-TP directed visibility graph method can more accurately represent SDO information and the SNG graph similarity matching method is applicable for all SDO data and can produce correct auxiliary evaluation results.