Low-density parity-check code is an excellent code with a fair approximation to Shannon limit, strong flexibility and simple description, which has been a research hotspot of channel error correction coding technology. Focused on a certain communication system, this thesis designs a codec system based on principle of LDPC codec with unique word insertion function and variable coding parameters from frame to frame for the purpose of adapt information transmitting to the needs under various circumstances; besides, by means of breaking information bit and check bit, the proposed codec system can therefore realize information encryption.Codec modules with different code lengths adopt multiplexing scheme, which refers to that RAM is designed according to the longest code length so as to reduce its resource occupancy. After analyzing the performance of the MSA decoding algorithm in the AWGN channel, the simulation results show that the proposed method can realize functions of adjustable multi-parameter LDPC codec system with excellent performance of information transmission and low resource occupancy rate, such as functions of code length, iteration number, break mode, unique word insertion, etc.