Aiming at the difficulties of controlling on potato late blight, maize northern and southern leaf blight diseases caused by the overlapping of rainfall and peak of these diseases in mountainous area of Southwest China, intercropping of potato with maize by adjusting planting time and spacing to avoid rainfall and disease occurrence was assessed. The results showed that early or late planting of potato, avoiding rainfall peak from potato vigorous growth and increasing light and air diffusion in space, alleviated potato late blight disease. The average severities decreased by 44.3% for potato late blight, 14.8% for maize northern leaf blight and 22.5% for maize southern blight, compared with the monocropped controls. Moreover, this kind of intercropping pattern improved the output significantly. The crop yields were increased and reached a land equivalent ratio (LER) of 1.738 for early planting pattern and 1.766 for late planting. This approach can be practical significance for ecological control of crop disease and food production increase. The agroecological structure in harmony with the natural environment results in ecological and cycle agriculture with high yield, high quality and high efficiency.