在工程量清单计价模式下，由于招标工程量与竣工工程量存在差异，投标单位采用不平衡报价，导致建设管理单位存在超概算的风险。在深入分析投标单位投标策略的基础上，构建不平衡最优报价模型，得出投标单位的最优报价；然后采用蒙特卡罗模拟法，构建了输变电工程造价风险评估模型，对建设管理单位所面临的风险进行了度量，并根据风险大小采取适当措施，尽量减少超概算情况的发生。研究结果对工程造价管理具有一定指导意义，可以规范招投标规则，使输变电工程建设健康、合理、可持续地发展。

In the bill-of-quantity model, as there are some differences between bidding engineering quantity and completed engineering quantity, the unbalanced quotation adopted by bidding companies may lead to the probable risk to construction companies. Based on the thorough analysis on the bidding strategies of bidding companies, the optimal unbalanced bidding model was built to acquire the optimum price quotation. Then, with Monte Carlo simulation method, cost risk evaluation model of power transmission and transformation projects was built to meature the risk of construction companies. The appropriate measures were used according to the risk scale, which could minimize the happening of excess budgetary estimate. The research results have guiding significance to the engineering cost management, and will standardize the bidding rules for the health, reasonable and sustainable development of the construction of power transmission and transformation projects.