An intelligent control system of a biomass gasifying furnace is invented against the characteristics of nonlinearity, poor stability, large time lag and strong interference of a biomass gasifying process. An intelligent control method of the biomass gasifying furnace comprises an intelligent integrated control method of biomass gasifying furnace double closed loops comprising a temperature control loop and a combustible gas oxygen content control loop. The temperature control loop adopts a main and auxiliary control structure: a main controller adopts a BP nerve network model to establish a BP nerve network model of the temperature; and an auxiliary controller realizes following control according to a temperature predication result. Feedbacks of the temperature and the oxygen content are introduced to the combustible gas oxygen content control loop, the main controller adopts fuzzy immune PID control, and reckons an optimal blower rotating speed; and the auxiliary controller realizes the following control of the blower speed. A simulation result shows the effectiveness and the superiority of the method.