In the practice of diaphragm wall construction, some important functions of the guide wall have been ignored, so the past experience-based design of guide wall is lack of scientificness. According to comprehensive analysis of functions of the guide wall, this paper puts forward the general safety design principle for the guide wall of ultra-deep rectangular diaphragm wall, and deduces the formulas of depth, width, anti-sliding,toppling through force analysis for purpose to instruct the design of guide wall scientifically. It also puts the design theory into practice in one rectangular diaphragm wall quay project.