The Objective of the present study is to compare the sealing ability of high-temperature thermoplasticized injectable technique and cold lateral condensation. 68 fresh in vitro teeth were divided into four groups: Group A (30 teeth), Group B (30 teeth), Positive Group (4 teeth), and Negative Group (4 teeth). In Group A, high-temperature thermoplasticized injectable technique was used, while in Group B, the cold lateral condensation technique was used. The root canal filling time, leakage phenomenon, sealing ability and compliance were compared in these groups. In Group A, the root canal filling time (6.48±0.45 min) and leaking length (1.02±0.14) were significantly lower than in Group B. The sealing capacity of 1.5mm, >100 and <250 root canal 1.5mm, and ≥250 root canal 1.5mm and 3.5mm (0.9485±0.0218, 0.9504±0.0152, 0.9452±0.0147, and 0.9522±0.0142), and the compliance of 1.5mm and 3.5mm (0.9558±0.0164 and 0.9722±0.0142) were significantly higher in Group A than Group B (P<0.05). Hightemperature thermoplasticized injectable technique can reduce the filling time, increase compliance, and has good sealing effects on root canal.