Phase transition of liquid crystal carboxylate from crystalline state (K) to smectic phase B (S-B) is investigated by low-frequency internal friction (IF) and I)SC method. The IF peak temperature increases with the increase of heating rate, but it has no clear dependence on vibration frequency. The experimental results agree with the characters of the low-frequency IF associated with first-order phase transition, and the change in the quantity of phase interface is responsible for the IF peak.