Multi-functional measurement and control devices are key equipment in a power automation system. Its core chips rely on imports. This threatens the safety of the power grid. The current situation is that few domestic chips suitable for a power automation system and some peripheral chips do not have suitable models, and this is combined with the demand for multi-service integration. This thus requires platform improvement and key technologies for multi-functional measurement and control devices based on domestic ARM and FPGA. First, this paper designs a hardware platform based on FPGA programming to replace chips without suitable models to fix intelligent I/O technology. Then, based on data sharing and FPGA collaboration, a software platform is designed. Given the current situation of domestic chip manufacture, improvement technologies are proposed to compensate for measurement accuracy and to reinforce reliability and expand functions. Finally, the above platform designs and improvement technologies are integrated and the multi-function measurement and control device is developed based on domestic chips. Its performance is verified by third-party professional testing and meets the requirements of relevant standards, and it has been officially put into operation in substations with good conditions.