Objective:To observe the growth of type Ⅱ alveolar epithelial cell(AECⅡ) and dynamic expression of AECⅡ specific protein ATP binding cassette transporter A3(ABCA3) in vitro. Methods:Lung tissues of 19-day fetal rats were digested with trypsin and collagenase,then screened for AECⅡ with different centrifugal force and repeated attachment. AECⅡ was identified by electron microscopy. Growth status and shape of attached cells in different time were observed with inverted phase contrast microscope,and the cell growh was assayed by MTT assay. The dynamic expression of ABCA3 in AECⅡ was detected by immunofluorescence. Results:The characteristic lamellar bodies of ACEⅡ with varying size and amount were observed under electron microscopy. The obsorbance value of AECⅡ cells by MTT at 24 h,36 h,48 h,72 h,96 h,120 h was 0.177 ± 0.009,0.193 ± 0.011,0.212 ± 0.019, 0.253 ± 0.019,0.243 ± 0.012,0.192 ± 0.011 respectively. Cell morphology under microscope gradually became elongating and flattening,and the intracellular particles gradually reduced. Simultaneously,the immunofluorescence assay result showed that ABCA3 expression in AECⅡ cells gradually decreased with the culture time prolonged. Conclusion:Primary cultured AECⅡ has the best growth status and the most abundant ABCA3 expression in the early culture time,therefore this period (primary culture for 72 hours or less) is optimum time to research mechanism of diseases associated with lung development.