In order to enhance the stability of the explosive null gate and reduce the requirements of the groove filling process in the applications, the method which used the detonating cord to replace the partial groove charge structure was proposed by taking the gap null gate as the research object. The combination experiments of detonating cord with different size parameters, groove charge and null gate gap were carried out, and the optimal filling material combination which has simple filling process and more stable control ability of the signal channel was expected to be obtained. Results indicate that the stability and reliability of the explosive null gate device can be guaranteed, and the parameters of the explosive null gate consisting of detonating cord be properly configured.