In order to investigate the method of pattern forming by the on-off control method in the v-bed flat knitting machine, the needle selection mechanism of the existing v-bed flat knitting machine was converted into newly contrived one which was controlled by the electronic logic circuit. The requirements of the electronic logic circuit and the pattern reading system of the v-bed flat knitting machine were examined. The operational results of the contrived needle selection mechanism by the electronic logic circuit and the pattern reading system showed that the newly contrived system was fully adaptable to the existing v-bed flat knitting machine.