Thermally stimulated depolarization current (TSDC) experiments were carried out to investigate the effect of polarization temperature (T (p)) on liquid-liquid transition and space charge detrapping behavior in atactic polystyrene. Differential scanning calorimetry (DSC) measurement was applied as a complementary method. When T (p) is 130 A degrees C, there are four distinct peaks (alpha, rho(1), LL, and rho(2)) showed in TSDC spectrum in the range of 30-200 A degrees C. Compared with the result of DSC, TSDC spectrum show that peak alpha corresponds to glass transition, peak LL is related to liquid-liquid transition, and peak rho(1) and peak rho(2) belong to the space charge current peak. As T (p) increases from 100 to 150 A degrees C, the intensity of peak LL maximum increases and that of space charge peaks maxima decreases, which is attributed to different mechanism between liquid-liquid transition and space charge detrapping behavior. In addition, their corresponding characteristic parameters versus T (p) are also analyzed in detail.