The mode I fracture toughness of an adhesive at low temperatures under high loading rates are studied experimentally. Typical R-curves of the polyurethane adhesive under different loading rates (0.5 mm/min, 50 mm/min, 500 mm/min) at different temperatures (room temperature, -20 degrees C, -40 degrees C) respectively are obtained. From the experimental results, the mode I fracture toughness of this adhesive is extremely sensitive to the high loading rates and low temperatures. With the increase of the loading rate and decrease of temperature, the mode I fracture toughness of this adhesive decreases significantly. Under the loading rate of 500 mm/min at -40 degrees C, the mode I fracture toughness of adhesive is 15% of the value at room temperature (RT) under quasi-static conditions. Through the experiment, the relationship between mode I fracture toughness of this adhesive, nominal strain rate and temperature is obtained.