For blind recognition of binary linear block codes in information interception, with the linear structure and checkout properties of block codes and characteristic weight distribution, this paper proposes a method of blind recognition of linear block codes under a high bit error rate condition based on matrix rank and the information entropy function of the weight distribution. The method can recognize code length using the information entropy of rank and precisely compute codes start bit based on the information entropy function of the weight distribution. According to the characteristic of systematic or non-systematic linear block codes,the generator matrix is accurately obtained using different calculation methods, and blind recognition of linear block codes is achieved. Simulation results show that this blind recognition method has good performance in the case of high BER.