Abstract: This paper proposes a novel component code,QC-LDPC code constructed by finite field method.It can improve the performance of objective QC-LDPC code effectively,when compared with the array code or shortened array code.In this paper,the background of QC-LDPC code is depicted firstly.Then,the QC-LDPC code design method based on CRT (Chinese Remainder Theory) is reviewed.Furthermore,the procedure of QC-LDPC code construction algorithm based on finite field method is given.Finally,the improved QC-LDPC code construction method based on CRT is described.Simulation results show that the finite field based QC-LDPC code can improve the performance effectively of the objective QC-LDPC code when adopted as the component code of the CRT method.