Abstract: This paper presents a new security encryption model based on improved LFSR（Linear Feedback Shift Register），which combines the high flexibility and low cost of the shift register and the characteristics of the high-speed and reconfigurable performance of FPGA，thereby allowing the system to achieve the purpose of low-cost，real-time allocation algorithm and reorganization of security policy document.This paper elaborates on the model of improved linear feedback shift register encryption algorithm encryption theory，and then introduces the FPGA algorithms and Reconstructable technologies.Finally，with the diagram analysis about the encryption and the valuation of total function，it is proved the arithmetic has good cost advantage and reconfiguration ability as safe is assured.