Abstract: Objective To explore the morphological characteristics and antibody expression patterns of adenocarcinoma cells in different tissues by liquid based cytology. Methods From April 2015 to July 2016， 90 cases of serous cavity effusion diagnosed as adenocarcinoma by histology in our hospital were collected， including 45 ovarian adenocarcinoma samples and 45 lung adenocarcinoma samples. Liquid based cytology was used to observe the morphological features of adenocarcinoma cells from different tissue origin and the expression patterns of carbohydrate antigen 125（CA125）， carbohydrate antigen 199（CA199）and carcinoembryonic antigen（CEA）were also investigated. Results As for ovarian adenocarcinoma，cells were arranged in clusters（tens to hundreds）in a round， oval， and papillary shape. There was often overlap and the edge was smooth with tightly packed cells. Caryoplasm is relatively high but the cytoplasm is relatively small. Small to medium or large nucleoli were visible with sand body in the background. Lung adenocarcinoma cells were arranged into pellets with abundant cytoplasm and strong mucus secretion. The cell mass is very three-dimensional， with large nuclei and obvious nucleoli. The positive expression rates of CA125 and CA199 in lung adenocarcinoma were 33.33%（15/45）and 28.89%（13/45）， lower than 71.11%（32/45）and 51.11%（23/45）of ovarian adenocarcinoma with significant difference（P<0.05）. The positive expression rates of three antigens in Ⅰ-Ⅱ stage of ovarian adenocarcinoma and lung adenocarcinoma samples were significantly lower than those of Ⅲ-Ⅳ stage（P<0.05）. Conclusion There were some differences in the morphological characteristics of adenocarcinoma cells from different tissues， and different expression patterns of CA125， CA199 and CEA had some value in judging the source of adenocarcinoma cells.