Power load is significant for the power system load forecasting, system planning, and so on. Because of its subject to weather, climate and the impact of social systems, it shows complex nonlinear characteristics. Especially when the electricity market is established, its nonlinear dynamics is also guided by the market mechanism. Facing to this, a study is done based on the load data of a certain node in Zhejiang Province grid, extracted its Hurst exponent and the box dimension, calculated the maximum Lyapunov exponent and the K entropy. It proves the nonlinear dynamic characteristics of power load under electricity market, and reconstructs its phase space.