The utility model relates to a continuous casting device for producing a round billet with the diameter being more than or equal to Phi 800 mm on a straight-form conticaster, which comprises a ladle (1), a ladle gyrating platform (2), a continuous temperature measuring device (3), a tundish (4), a nanometer heat preservation material (5), covering slag (6), a cooling water nozzle (7), a runner passage (10), an electromagnetic mixing device (11), a crystallizer (12), a crystallizer vibrating device (13), a guiding roller (14), a flame cutting machine (15), a capsizing device (16), a platform (17), a shot-blasting machine (18) and a burial pit (19), wherein the ladle (1) is arranged on the ladle gyrating platform (2), and the pouring box (4) is arranged below the ladle gyrating platform (2), and the crystallizer (12) is arranged below the tundish (4), and a round billet bottom part which is arranged below the guiding roller (14) is provided with the platform (17), and the side of the round billet which is arranged below the guiding roller (14) is provided with the flame cutting machine (15) and the capsizing device (16), and the burial pit (19) and the shot-blasting machine (18) are arranged nearby the platform (17). The continuous casting device can compensate the vast shrinkage mass which is produced during the pouring consolidation and can solve the stress problem during the cooling process.