Effect of using SrCl₂?6H₂O-SrCO₃and hydroxylate carbon nanotubes (CNTs) as composite nucleating agent on the energy storage properties in the induced crystallization nucleation process of MgCl₂?6H₂O-CaCl₂?6H₂O were investigated. It is suggested that the addition of CNTs can reduce system supercooling degree (SSD), which decreases with increased CNTs. When the composite nucleating agents consisting SrCl₂?6H₂O-SrCO₃ and CNTs were introduced SSD can be further decreased when the composite nucleating agents consisting SrCl₂?6H₂O-SrCO₃ and CNTs were introduced because of the good thermal conductivity and high phase change latent heat. SSD decreased to a minimum of 0.6 ℃ when the ratio of CNTs, SrCO₃ and SrCl₂?6H₂O was optimized as 0.25 wt.%、1 wt.% and 3 wt.%, respectively.