Electricity spot market clearing results are affected by market participants’ bids and various coupling constraints. A rational explanation offers insight into the causes of market clearing results, as consequence, improves market operators’ ability to organize spot market transactions and mitigate risks. The paper proposes a comprehensive analysis method for day-ahesd spot market clearing results. On one hand, based on the existing operating experiences and optimization principles for market clearing, the method screens key states of unit dispatch plans and grid safety, and analyze the causes. On the other hand, based on the Pearson correlation theory and isolated forest algorithm, untypical clearing prices can be located speedily and analyzed combining with physical laws of power grid operations. At last, based on a provincial spot market case, the paper locates untypical states for unit opertaion, grid operation and clearing prices and gives explanations for them, which verifies that the proposed method can provide foundations of the disclosed spot market information, and improves the explainability of the spot market clearing results.