The initial temperature distribution of the combustible mixture has a significant effect on the measurement accuracy of the laminar burning velocity using the outwardly propagating spherical flame method. In the present study, the initial temperature fields inside the constant-volume combustion vessel were obtained by different arrangement methods of heater. Further, the effects of the non-uniformity of initial temperature field on the propagation processes of two-dimensional premixed H-2-air laminar flames were numerically studied. The results show that when the initial temperature field inside the vessel heated by heating tapes reaches a stable state, the temperature of H-2-air mixture tends to descend first and then rise along the gravity direction, which indicates that the non uniformity of the temperature field increases with the actual delivered power. Compared with the uniform initial temperature field, the maximum relative deviation of laminar burning velocity of H-2-air mixture obtained in the non-uniform initial temperature field is 7% when the vessel is heated by heating tapes under the power of 669 W. However, the non-uniformity of the initial temperature field of the H-2-air mixture in the vessel obviously decreases and the maximum relative deviation of laminar burning velocity is only 2% when a simulated evenly arranged heater is employed to heat the vessel. Consequently, it is quite necessary to evaluate the non-uniformity of the initial temperature field inside the constant-volume combustion vessel before using the outwardly propagating spherical flame method to determine the laminar burning velocity. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.