The invention discloses a kitchen fire alarm system and method for human body detection in front of a cooking bench. The system comprises a flame detection module, an analog-to-digital conversion module, a data transmission module, a main control module, a combustible gas detection module, a GSM communication module, a human body detection module, a temperature detection module and a distance measurement module. The method comprises the steps that the main control module calculates a combustible gas concentration value, a flame concentration value and a temperature value and compares the values with corresponding alarm thresholds; when any numerical value of the combustible gas concentration, the temperature and the flame concentration is detected to exceed the preset alarm thresholds, thehuman body detection module detects infrared rays emitted by a human body in front of a cooking bench, the distance measurement module measures the distance between the head of the human body in front of the cooking bench and the alarm system, and the main control module calculates the height of the human body in front of the cooking bench and selects whether to send alarm information or not. Before the kitchen fire alarm information is sent, the human body in front of the cooking bench is detected, and the practicability of the kitchen fire alarm system is improved.