With the continuous development of society and the continuous progress of information technology, people's demand for electric energy is increasing. At the same time, with the vigorous promotion of renewable energy in various countries, the growth of power scale has been further strengthened. The traditional power system can no longer meet the needs of today's power industry, and the concept of smart grid has been put forward. Previous studies have shown that attackers can launch injection attacks on smart grid power system, thus affecting the normal operation of power system state estimation. This paper presents a random number based violence injection attack method without power system topology information. The influence of the proposed attack method on the state estimation of smart grid power system is studied in the state estimation based on weighted least squares and Kalman filter. The simulation experiment is carried out on the ieee-14bus simulation system to simulate the attacker's attack on the power system, and two different state estimates are analyzed and discussed.