An in vitro spheriod invasion model of tumor cell was established by using murine lung adenocarcinoma cell line (LA795) and precultured embryonic chick heart fragment (PHF). The spheroid of LA795 cells were prepared by incubating a suspension of trypsinized LA795 cells on a gyratory shaker. Spheroid aggregates of LA795 cells in diameter of 0. 2 mm were selected and confronted with PHF (diameter of 0. 4 mm) on semi- solid medium for 3 - 4 hours, then, individual confronting pain were transferred into fluid medium for further co-culture on gyratory shaker. After 1, 3, 5 and 7 days, multiple confronting pairs were processed for histological and ultrastructural study. The Invasive capacity and the invasion process of LA795 cells were examined and observed. The results demonstrated that LA795 cell line has a high capacity of invasion and high malignancy in vitro. This spheroid Invasion model is very useful for studying mechanism of Invasiveness of tumor cells in vitro. An in vitro spheriod invasion model of tumor cell was established by using murine lung adenocarcinoma cell line (LA795) and precultured embryonic chick heart fragment (PHF). The spheroid of LA795 cells were prepared by incubating a suspension of trypsinized LA795 cells on a gyratory shaker. Spheroid aggregates of LA795 cells in diameter of 0. 2 mm were selected and confronted with PHF (diameter of 0. 4 mm) on semi-solid medium for 3 - 4 hours, then, individual confronting pain were transferred into fluid medium for further Cosmic on gyratory shaker. After 1, 3, 5 and 7 days, multiple confronting pairs were processed for histological and ultrastructural study. The Invasive capacity and the invasion process of LA795 cells were examined and observed. The results demonstrated that LA795 cell line. Has a high capacity of invasion and high malignancy in vitro. This spheroid Invasion model is very useful for studying mechanism of Invasiveness of tumor cells in vitro.