Tumor microenvironment dissection from pathological images is informative in lung adenocarcinoma (ADC) diagnosis. However, manually recognize and localize each cell in gigapixel pathological slides are almost impossible. Here we describe our development of the first automated cell type classification pipeline involving nuclei segmentation, convolutional neural network based tumor/stroma/lymphocytes classification, and feature extraction for lung ADC pathological images. The overall classification accuracy is 92.9% and 90.1% in training and independent testing datasets, separately. The extracted 6 simple features describe spatial distributions of different cell types and are prognostic for lung ADC. An image feature based prognosis model is developed and independently validated. The predicted risk group serves as an independent prognostic factor, after adjusting for clinical variables including age, gender, smoking status, and stage.