To study the effect of sample width and inclined angle on flame spread across expanded polystyrene (EPS) surface, a series of laboratory-scale experiments were conducted in the Lhasa plateau and the Hefei plain. Surface flame height, flame spread rate and preheating zone length were obtained. The dimensionless surface flame height varied as the -n power of the sample width and 0.7 < n < 0.9. As angle of incline increased, the surface flame height first rose and then dropped. The surface flame height difference between maximum and minimum width became smaller with the increase in angle of incline. With an increase in sample width, the flame spread rate first dropped and then rose where the angle of incline was small, while the trend was reverse for samples with larger angle of incline. For EPS at 15°and 30°, the trend of flame spread rate versus sample width in Lhasa was inverse, compared with the results obtained in Hefei. The variation trend of preheating zone length with sample width and inclined angle was different from the flame spread rate trend. However, a linear relationship of v_f/w and _ph/w was found in Lhasa plateau. The surface flame height, flame spread rate and preheating zone length in Hefei plain were larger than the results obtained in Lhasa plateau. The experimental results agreed well with theoretical analysis.