The power load sampling data of electrical appliances is the foundation for studying non-intrusive load monitoring methods. A device specifically designed for residential electrical appliance load data acquisition, which is connected to the power grid through a power supply cable. The device panel is designed with two 16 A sockets side by side. Household appliances can be directly plugged into the sockets like using sockets to obtain power. A precision voltage and current sampling circuit have been designed inside the data acquisition device. The circuit, in conjunction with an analogue-to-digital converter, can transform the analogue voltage and current signals into digital signals during the operation of household appliances. The designed device has been applied to collecting voltage and current waveform data of electrical appliances in over 200 households, and an automatic load characteristics extraction program is designed to process the collected power load sample data. The load characteristics of different electrical appliances during operation have been extracted and calculated. The principal component analysis method has been used to analyze the load characteristics of various electrical appliances quantitatively. The characteristic principal components of various appliances are obtained through the above method, which is able to provide a basis for the design of non-intrusive load identification algorithms.