AbstractBoron nitride (BN) coated with sulfonated poly-arylene ether nitrile (SPEN) (BN@SPEN) was used as additive to enhance the thermal conductivity of polyarylene ether nitrile. BN@SPEN was prepared by coating BN micro-platelets with SPEN through ultrasonic technology combined with the post-treatment bonding process. The prepared BN@SPEN was characterized by FTIR, TGA, SEM and TEM, which confirmed the successful coating of BN micro-platelets. The obtained BN@SPEN was introduced into the PEN matrix to prepare composite films by a solution casting method. The compatibility between BN and PEN matrix was studied by using SEM observation and rheology measurement. Furthermore, thermal conductivity of BN@SPEN/PEN films were carefully characterized. Thermal conductivity of BN@SPEN/PEN films was increased to 0.69 W/(m⋅K) at 20 wt% content of BN@SPEN, having 138% increment comparing with pure PEN.