The range and longitudinal intensity of base-bleed projectile are closely related to the working performance of igniter. The combustion expansion characteristics of igniter with different orifice diameters(6.5, 8 mm) for five kinds of ignition agents, magnesium/polytetrafluoroethylene (MT) (Mg/PTFE 45/55, Mg/PTFE 55/45, Mg/PTFE 61/39), barium nitrate (Ba (NO₃)₂) and zirconium hydride/lead oxide (ZrH₂/PbO₂ 40/60), were investigated in the atmospheric environment by using high-speed camera system and infrared thermal imager and then the flame temperature field distribution of seven kinds of igniters was measured. On the basis of experiment, the cell-centered finite volume method based on internal nodes was applied to three-dimensional numerical simulation of the combustion jet field of MT igniter. The distribution rule of combustion characteristic parameters of the igniter in the atmosphere under different mass ratios of MT and orifice diameters of the igniter was analyzed. The experimental and numerical results show that ZrH₂/PbO₂ igniter will destroy the "parallel layer" combustion law of base bleed propellant. The ignition area effective factor is proposed to represent the significant degree of the propellant ignition area, and is combined with the ignition time to synthetically evaluate the ignition performance of the igniter. It is found that the MT igniter with mass ratio of 61:39 and orifice diameter of 8 mm is the best. The maximum flame temperature region of igniter is located above the potential core of the nozzle. The smaller the magnesium content in the range of 0.45-0.61 is, the higher the flame temperature in the combustion field of the MT igniter. When the magnesium content is constant and the orifice diameter of igniter is 6.5 mm and 8 mm, the larger orifice diameter has the stronger heat convection in the combustion field, the higher center axial temperature and the greater temperature gradient.