The heat release performance of liquid cooling plate for motor controller was experimentally investigated using subnanometer silver fluid and 50% ethylene glycol-water solution as the coolant. At an inlet temperature of 70 ℃, the temperature difference between the inlet and outlet of liquid cooling plate and the heat source temperature were measured under varying flow rates and heating loads of 2.5 kW, 3.5 kW, 4.5 kW, and 5.5 kW. The heat release efficiency was subsequently analyzed. The results indicated that, at a heating load of 5.5 kW and a mass flow rate of 0.22 kg/s, the liquid cooling plate using subnanometer silver fluid with a mass concentration of 700×10^-6 exhibited 6.28% increase in the inlet-outlet temperature difference, and a 6.8% improvement in heat release efficiency compared to the 50% ethylene glycol-water solution.