To achieve the high system integration, reasonable structure and layout, advanced and applicable equipment, energy conservation and environmental protection of economy as well as supporting control integration, the new generation smart substation puts forward the requirement of multifunctional measurement & control device, which integrates measurement & control, metering of no gateway and synchronized phasor measure in an interval. The paper describes the specific function and hardware & software framework of multifunctional measurement & control device. All key technologies are analyzed and summarized to meet the higher requirement of software and hardware of multifunctional measurement & control device. Theoretical simulation and practical test verify that the proposed specific technical algorithms, such as data merge and reactive power algorithm based on Hilbert transform, can improve computational efficiency and accuracy of data and solve the technical problems of developing multifunctional measurement & control device. Specific application in demonstration project of new generation smart substation indicates that the multifunctional measurement & control device can reduce the number of secondary equipment and increase integration of substation secondary system.