The paper deals with the saddle shape cable roof, which is supported by tenswion cables. The saddle shape and prestressing enable to provide stability of the roof surface during the action of alternating loads and to consider light composite materials for roofing. Steel cables are considered as cable net material. The main rational geometrical characteristica are evaluated by the numerical experiment for the structures with sizes in plan from 10 to 50 m for the case, when support points of the cable roof have displacements, which are limited by the deformations of the anchors. the numerical experiment was conducted for the static loading case. the main geometrical characteristic are the initial deflections of stressing,suspension and tension cables and the step in plan of suspension and stressing cables.