Abstract: A new class of (2k,k,1) convolutional codes are created by combining double cyclic codes and (2,1,1) convolutional codes, and also a new method for creation long codes with short ones was proposed. The structural mechanism of the codes was revealed by defining a state transition matrix and using algebraic method as well as grille graph. This code structure was excellent in both proportionality and diversity, besides, the distance characteristics of it are also quite well. Simulation results show that, the (2k,k,1) convolutional codes present some advantages over the traditional one in error correction performance and decoding speed.