With the development and proliferation of smart grid and the relevant techniques, smart the electricity monitor is increasingly important for improving the overall performance of power network. With a number of new attributes, the smart electricity monitor is significantly different from these conventional electricity meters. For example, it actively provides the information for the management, reliability and maintainability purposes and acts as an irreplaceable component in the power network. In this paper, we mainly focus on the design and implementation of the smart grid which integrates a series of innovative functions, for example demand forecasting and status estimation. Specifically, the research backgrounds pertaining to this field will be briefly introduced and the state-or-the-art mathematical models related to both demand forecasting and status estimation will be constructed accordingly. Also, to investigate their feasibility and efficiency, a set of simulations based on MATLAB will be conducted and the simulated results will be presented. Finally, a complete and innovative prototype of smart electricity use monitor integrating forecasting and status estimation functions can be constructed, verified and analysed in depth by both of mathematical expressions and simulated results.