In this paper, a series of composite PCMs based on the comb-like polymer, poly(tetradecyl acrylate) (PTA), is developed via a solution-blending method with boron nitride (BN) as the thermal conductors that vary from 5%, 10%, 15% to 20%. The structure, thermal performance, energy storage and release capability, cycle stability are deeply characterized. The thermal conductivity of PTA/BN composite PCMs increases to 0.62 W/mK at 20% BN, displaying 113.8% higher than that of pure PTA (0.29 W/mK). The PTA/BN composite PCMs present a good energy storage ability, and the maximum temperature difference, -22.3 °C, and 475 s thermal buffering time at 50 °C are achieved for the coated fabric by 0.96 g PTA/BN-20% composites. And, the fabrics coated by PTA/BN-20% demonstrate good structure stability with no thermal energy loss after 5 thermal cycles. In the meantime, a comparable temperature increases to 6.1 °C is displayed for the bottle covered by the PTA/BN PCMs coated fabric, followed by a stable thermal energy storage ability during the 5 min heating process, expressing the good thermal conductor of the BN sheet. This result opens a promising application for the thermoregulated fabric with a controlled thermal conductivity and thermal energy storage ability.