Fourteen kinds of Chinese coal were flash hydropyrolysed in a small entrained reactor at 750 degrees C and hydrogen atmosphere. The results indicated that carbon content and yields of liquid hydrocarbon, H/C and yields of gaseous hydrocarbon, oxygen content and yields of CO, CO2 and H2O show better corresponding relations. The correlations between yields of CH4, C-2 and C2H6 and H/C can be expressed as Y-CH4 = -42.2 + 100(H/C)(0.51 < 0.59), Y-CH4 = 15.8 + 1.67(H/C)(0.59 < 1.11), Y-C2 = 0.347 + 4.78(H/C), Y-C2H6 = 0.352 + 4.74(H/C); The correlations between yields of CO2 and water and oxygen content can be expressed as: Y-CO2 = - 0.0437 + 0.0355(0); Y-H2O = 0.726 + 0.467(O). The cutoff points of flash hydropyrolysis for coal are that H/C is 0.6 and carbon content is 85%. The coal which H/C is lower than 0.6 and carbon content is higher than 85% is usually not good for flash hydropyrolysis. It is found that influence of coal rank on yields of liquid, gas product and total yields of product in flash hydropyrolysis can be expressed as of H/C in coal.