The Grid-connection of large-scale intermittent generations brings new challenges to transmission networks (TN). Based on the analysis of life cycle cost (LCC) of TN, taking TN planning as the main decision issue and reliability assessment as a sub-issue, a master-slave relationship of hierarchical decision is formed. Using the multilayer programming theory, a bi-level programming model of TN is proposed. The upper level aims at the optimal LCC and generates a planning scheme. Considering the uncertainties of intermittent generation outputs, loads and line outages, a linear dc stochastic optimal power flow model (SOPF) is formulated to assess the reliability of the generated scheme on lower level. Hybrid algorithm combined an improved deferential evolution algorithm, three-point estimate method and linear programming is adopted to solve the proposed model. Results of 18-bus system show feasibility and validity of proposed method.