The information of diesel spray in a stable hot coflow (300—673 K) is recorded with a highspeed camera and a laser diffraction instrument. The results show that as the coflow temperature increases, the spray penetration decreases and a peak spray angle appears. When the coflow temperature is equal to 300 K, the Sauter mean diameter of the droplets is between 10 μm and 20 μm and slightly increases along the axis. Dv90 decreases by 17% from 20 mm to 40 mm in the axial distance. The size distribution parameters decrease along the radius. The uniformity of the droplet sizes becomes better as the axial/radial distance increases. The Sauter mean diameter increases from 15 μm to 24 μm and the uniformity increases as the coflow temperature increases from 300 K to 673 K, owing to the fast evaporation of small droplets.