The safety planning of hydropower engineering construction equipment involves great difficulty. Based on space-time analysis and motion analysis, we proposed a theoretical system of safety planning for machinery and equipment. First, we presented the basic conception including the definition of spatial model, the quantitative description of construction space, and the space projection transform, etc. The safety planning system includes the safety evaluation criteria of construction objects, the evaluation criteria of machinery and equipment in the construction site, and the safety indexes of construction layout. This theoretical system provides a new approach for the research of construction safety planning, and helps evaluate the safety problems during the construction, thereby reducing or eliminating safety accidents.