This paper reports the thermal and electrical stabilities of three GdBCO single-pancake coils,one impregnated with epoxy only (coil 1),another impregnated with epoxy/AlN composite (coil 2),and the other impregnated with epoxy/BN composite (coil 3).In cool-down tests from room temperature to 77 K,the cooling time of coil 3 (356.3 s) was faster than those of coil 1 (468.1 s) and coil 2 (429.8 s),because the addition of BN filler which exhibits superior intrinsic thermal conductivity (300 W/m·K) effectively increased thermal conductivity of the epoxy composite.