Under the background of incremental distribution reform, the local grid and the incremental distribution network will directly participate in the electricity spot market, and compete with main power supplies in the market segments of quotation, clearing, pricing, and settlement, etc. Local grid enterprises and incremental network enterprises will also directly participate in the competition of the spot market, which will exacerbate the risks of price fluctuation, information disclosure, and network congestion in the spot market. In order to help enterprises identify and evaluate market risks, develop scientific risk prevention strategies, firstly, the risk impact mechanism of local grids and incremental distribution networks on the electricity spot market was analyzed; then, indicators were selected from five dimensions, such as competing risk and price risk, and a risk assessment model of the electricity spot market with consideration of local grids and incremental distribution networks was established; finally, strategic suggestions for preventing market risks were put forward, which provide a reference for rationally controlling the market risk of the spot market and promoting the safe and stable operation of the market.