To improve the heat dissipation performance of the Ternary Polymer Li-ion Batteries(TPLBs) in hot climate, a heat dissipation method including different PCMs (Paraffin, 10% GNP + Paraffin, 10% EG + CPCM) was established, and orthogonal test and fuzzy grey correlation analysis method were applied to investigate the heat dissipation effects of the TPLBP in hot climate. The results shown that the TPBP with 10% EG CPCM is of heat dissipation characteristics and thermal security (namely the temperature difference is less than 5K), it makes sure the safety operation of new energy vehicles under 3C in hot climate. And the fuzzy grey correlation values between the thermal conductivity λ of the PCM and the time τ0 of melting point appearance of the PCM in the TPLBP is of a maximum value of 0.5660, and the fuzzy grey correlation values between the discharge current I and the time τ0 of melting point appearance of the PCM in the TPLBP is of a minimum value of 0.3386. Therefore, the discharge current I has the greatest effect on the liquid phase composition ω of PCM, but also has the least effect on the time τ0 of melting point appearance of the PCM in the TPLBP.