Recently, the safety of electric vehicles using lithium-ion batteries has received increased attention due to overheating. Cold plates can effectively enhance heat dissipation. However, given the defects of existing cold plates, such as complex structure and heavy weight, a simple cavity cold plate is designed. The effects of cold plate inlet and outlet sizes (d2 and Δd), mass flow rate of coolant (W), and the inlet and outlet position on cell's maximum temperature and temperature difference are analysed using computational fluid dynamics (CFD) to enhance the heat dissipation capacity of the cold plate. Results show that the inlet and outlet sizes are positively correlated with the cell's maximum temperature. In addition, the cavity cold plate can satisfy the requirements of battery temperature difference by optimizing the inlet and outlet sizes and W. The cooling system of Model Z has better heat dissipation capacity than that of Model N. Conclusions obtained in the study have important reference for optimization of cavity cold plates.