From the foundational theory of explosive magnetic flux compression generator (MFCG), the inductance, resistance and current of non-symmetrical multi-branch helical MFCG have been calculated. And discussed the operation character of high inductance MFCG with low inductance load. An effective way of obtaining high energy gain of MFCG is to increase the ratio of its initial inductance to load inductance by increasing the initial one. It can provide a better voltage flat increasing number of helical coil sections and wires in parallel.