It is difficult to plant grass on rocky slope during road bio-technique const ruction, because the key techniques are related to the features o f rocky slope, plant selection, and the optimization compound ratio of planting material .By taking the Loudi section of Louzhan Railway Line as an example, the environmental characteristics of the slope are analyzed and parameters correlated to slope vegetation protection for weathered rocky slope are studied .The grass composition based on laboratory seeding test is optimized by root growth and germination rate of grasses for slope protection .The influence o f main component parts of planting material on its strength is analyzed according to laboratory normal experiment .The schemes for optimum compound ratio of planting material are achieved, which make its strength maximum in different periods of rainfall after construction .Technology of the spraying, the coverage, and the later period management are practiced to ensure the implementation of mixly spray for rocky slope greening under the hot and rainy weather successfully .