An approach to improve premixed hydrogen/air combustion in micro combustor is numerically studied in this paper. The micro-combustor with slits on both sides of the bluff body shows better combustion efficiency and uniformity of temperature distribution. The effects of the controllable flow ratio (gamma) and the angle of bluff body (theta) on combustion characteristics are investigated by using a two-dimensional model with the H-2/O-2 reaction mechanism. The results show that the increase of controllable flow ratio and angle of bluff body can improve combustion efficiency and decrease velocity extinction limit. However, at higher theta, increasing gamma do not play an important role in improving combustion efficiency. In addition, at higher inlet velocity, combustion efficiency do not increase dramatically with the increase of theta. Moreover, at high inlet velocity, a special phenomenon of temperature 'waist' is observed in the micro-combustor with slits on both sides of the bluff body, which has a huge impact on combustion characteristics. Therefore, controllable flow ratio and angle of bluff body should be reasonably chosen to improve combustion characteristics. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.