The invention discloses a radial combustor and an automatic control method thereof. The radial combustor comprises a combustor outer shell, a combustor inner shell, an inner shell space partition plate, a stepping motor, a base and an adjustable cylinder, wherein a mixture runner is formed between the combustor outer shell and the combustor inner shell; the inner shell space partition plate divides the space defined by the combustor inner shell into a fuel pressure stabilization cavity and a control mechanism installation cavity; the stepping motor is located in the control mechanism installation cavity; the base is fixed on the combustor inner shell, a groove is formed in the base, and a bending blade is arranged on the base; the adjustable cylinder is inserted into the groove of the baseand penetrates through the base to be matched with threads on a screw rod driven by the stepping motor, and the adjustable cylinder is provided with a fluid inlet; and the stepping motor can drive the adjustable cylinder to move upwards or downwards, and therefore the shielding area of the base on the fluid inlet can be adjusted, and the flow of the fluid in the adjustable cylinder can be adjusted. According to the radial combustor, the phenomena of flameout and tempering can be effectively avoided, and the combustion stability of a nozzle is improved.