A comparison of apical leakage produced by three preparation technique and two obrutation methods was done in this article.The fine curved canals were prepared with routine prepartion technique,ultrasonic technique,step-back technique and filled with traditional lateral condensation,warm gutta-percha lateral condensation separately.The result showed that the apical sealing ability of warm gutta-percha lateral condensation was superior to traditional lateral condensation.It could remedy the defect of irregular canal shape of fine curved canal preapred with routine technique and ultrasonic technique in some degree by the improvement of apical sealing ability.