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Research and development on polymer composites with high thermal conductivities and ideal thermal stabilities have become one of the hot topics in functional composites. In this work, boron nitride nanosheets/polyvinyl alcohol (BNNS/PVA) thermally conductive composite films were respectively prepared from ball milling (BNNS/PVA-I), directional freeze-drying (BNNS/PVA-II) and electrospinning technology (BNNS/PVA-III), followed by hot-pressing method. BNNS/PVA-III thermally conductive composite films had better comprehensive properties than that of BNNS/PVA-(I-II) composite films. Thermal conductivity coefficient in vertical direction (λ_⊥) of the BNNS/PVA-III composite films with 30 wt% BNNS was 1.031 W/mK, obviously higher than that of BNNS/PVA-I (λ_⊥ of 0.573 W/mK) and BNNS/PVA-II (λ_⊥ of 0.694 W/mK), respectively. And the λ in parallel direction (λ_∥) was significantly enhanced to 18.630 W …