It is proved that fuel efficiency promotion is an important method to improve the fuel economy and power output of direct-injection (DI) gasoline engines; moreover, the quality of fuel combustion is a critical factor for fuel efficiency. In DI gasoline engines, the diffusion and atomization of fuel spray are influenced by the airflow in cylinder when the spray is injected into the cylinder. The experimental measurements and theoretical analyses in this study are based on the conditions of cross-flow whose direction is perpendicular to the direction of spray. The spray images under various velocities and pressures of cross-flow were recorded using high-speed photography; besides, the spray area and spray volume were calculated from the spray images. To understand the movements of spray under the cross-flow conditions, the movements of single droplets with various diameters were deduced using aerodynamics methods. Under a constant velocity of the cross-flow, the diffusion of spray under a low ambient pressure is more distinct than that under a high ambient pressure. (C) 2017 Elsevier Ltd. All rights reserved.