In order to study the influence of environmental factors on the basic errors of single-phase smart meters, a method combining mathematical modeling with experiment was adopted. Starting from the components and considering the three key environmental factors of temperature, humidity and magnetic field, the mathematical model of basic error and environmental factors of single-phase electricity meter is established. The research shows that the influence of temperature on single-phase electricity meter mainly acts on resistors, shunts, measuring chips and voltage reference, and humidity mainly changes the aging characteristics of circuit boards and electronic components, thus affecting errors. Distribution of stray capacitance affects the error. The magnetic field mainly acts on the current loop to generate additional induced potential. In order to further study the influence of three factors on the error of electricity meter, a set of orthogonal experiments with 3 factors and 5 levels was designed. The experimental data show that the temperature has a significant effect on the error of electricity meter, while the magnetic field and humidity have no obvious effect on the error of watt-hour meter.