PEVTs and AEVTs are currently two kinds of typical EVTs in operation in power grid, but they would be required to calibrate error characteristics again before the operation. In order to research error characteristics of EVTs in three state of laboratory and field off-line and on-line operation, PEVT and AEVT samples from two mainstream manufacturers were selected to carry out the comparative study of error characteristics. The results show that the effect of the testing environment on ratio error of PEVT is less than 0.05%; however, the variable quantity of ratio error in laboratory is 4.3% with the temperature in - 40℃~ 53.5℃ and 0.55% in on-line operation in the temperature range of - 20℃ ~ 40℃. The ratio error of AEVT is sensitive on the test environment with the error from laboratory 0.03%, off-line scene 0.18% and on-line operation 0.36%; but the variable quantity of ratio error in laboratory is 0.21% within the temperature range of - 40℃~ 63℃ and 0.1% in on-line operation within the temperature range of - 20℃ ~ 40℃. In addition, the temperature characteristics of EVTs were sensitive to temperature gradient, and the temperature characteristic in on-line operation is better than in laboratory.