Abstract: cases malignant pleural effusion that taken place recently 7 year in the Zhuhai region were collected in this paper. Drawing conclusionscome from those attack trend morphological observation: 1. The high attack group age in positive cases is between 50 and 79 yrs (85% ). 2. there is an obvious difference in sexual distinction for the special high attack group (60-69 yrs).A ratio of male female is one to ten. 3. Adenocarcinoma occupay 90. 7 percent (49 cases), squamous carcinoma occupay 5. 6 percent (3 cases), undifferentiation carcinoma occupay 3. 7 percent (2 cases). 4. Not only dropping cancer cells but cancer organization may be observed, later is only in the adenocarcinoma cases.Sometimes dropping normal pleura tissue also may be seem. 5. The mucinous signet-ring cancer cells in high differentiation small cell adenocarcinoma should be differential diagnosis from mesothelium signet-ringoid change. 6. Sediment that being in hematoid or non-hematoid pleural effusion both should be made paraffin section as a routine diagnosis. This comparison study on method may help each other for accurate diagnosis.