ABSTRACTNano‐SiO2/UHMWPE/HDPE blend microporous membranes (NBMs) with different content of nano‐SiO2 particles were prepared via thermally induced phase separation process. Thermogravimetric analysis was used to investigation of the amount of nano‐SiO2 particles reserved in NBMs. This approach showed that about 59% of total content of nano‐SiO2 particles reserved in NBMs. The formation and development of the interface pores were studied by scanning electron microscopy. NBMs performance was characterized by a variety of metrics including thermal shrinkage, melting and crystallization behavior, porosity and pore diameter, and permeability. The results indicated that nano‐SiO2 particles served as nucleating agent increasing the crystalline of NBMs. The comprehensive properties of NBMs were optimum when the content of nano‐SiO2 particles was 1%. Compared with pure HDPE separators, NBMs exhibit higher porosity and lower thermal shrinkage due to its high crystalline and the enrichment of UHMWPE chains. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41321.