The invention discloses a 
metal-organic frame material based composite battery diaphragm and a preparation method and application thereof. The preparation method comprises the following steps: (1), synthesizing a 
metal-organic frame material precursor; (2), compounding the 
metal-organic frame material precursor and a two-dimensional material or a 
polymer material to obtain the metal-organic framematerial based composite battery diaphragm. The diaphragm is high in 
porosity and large in specific surface area, the 
electrolyte wettability of the diaphragm can be improved, and the 
ion transport number of the diaphragm is greatly increased; the diaphragm has the 
advantage of an adjustable pore size, and through a suitable pore size, shuttling of 
electrolyte ions can be effectively controlled, occurrence of adverse side reactions can be inhibited, the 
battery capacity can be increased and the cycle life can be prolonged; through a uniform pore structure, the passing ions can be uniformly dispersed on the surface of an 
electrode, so that growth of dendrites are fundamentally inhibited, the cycle life of a battery is effectively prolonged, and the safety performance of the battery is improved; the metal-organic frame material based composite battery diaphragm has good flexibility and mechanical properties and can be applied to 
assembly of a practical soft pack battery.