The invention belongs to the pesticide field and particularly relates to a synergic pesticidal composition with active ingredients to be the combinations of fipronil and a series of subspecies of Bacillus thuringiensis (Bt for short), wherein the Bacillus thuringiensis subspecies include six subspecies: Bacillus thuringiensis var.kurstaki, Bacillus thuringiensis var.aizawa, Bacillus thuringiensis var.tianmensis, B.thuringiensis var.israelensis, Bacillus thuringiensis subsp.aizawai and Bacillus thuringiensis subsp. kenyae. The main agent thereof includes the following active ingredients by the weight percentages as follows: fipronil 0.1%-80%, Bacillus thuringiensis 100-100000 IU (international unit) / mg, or 10-1000 billion spore / g, or 0.01-20% toxin protein, and the rest is an accessory ingredient. The pesticidal composition can be efficiently used for controlling agricultural pests such as rice leaf rollers, chilo suppressalis walkers, diamondback moths, prodenia lituras, corn borers, and so on, and has particular characteristics of high efficacy, long lasting period and safe usage, so that the pesticidal composition belongs to environment-friendly pesticides and can prolong the generation of resistance, reduce production cost and increase economic benefit.