Abstract The temperature dependence of AC susceptibility has been measured as a function of AC amplitude and frequency at zero DC field in MTG-YBa2Cu2.99Li0.01Oy crystals. We try to extract the critical current density near Tc from the real component of AC susceptibility curves. The temperature dependence of critical current density followed Jc(T) = 1.548 × 1010 (1 − T/87.3)1.38 (A/m2), which is good agreement with J c ′ ( T ) = 1.492 × 10 10 ( 1 - T p / 87.3 ) 1.36 ( A / m 2 ) obtained from the traditional “loss-maximum” approach. The effective activation energy near Tc is also discussed.