This paper introduces the principle of adaptive beam-forming technique, and presents a mathematical deduction to the algorithm in detail.A Global Navigation Satellite System (GNSS) anti-jamming method based on the adaptive beam-forming technique is proposed.Taking the circular antenna array with seven units as an example, the response of array is deduced, and a method for solving covariance matrix of the received signal is given.Therefore, the adaptive beam-forming technique can be used in the anti-jamming system of GNSS.The results of the simulation show that:this method keeps a gain with certain level in the direction of satellite signal and forms deep null in the direction of jamming, thus can have a good anti-jamming effect.