In order to find out the range of errors in measuring the size of public drawing information, this experiment measured the size at 24 places through 6 different measurement methods. The sample data analysis shows that the sample average error of measurement method 1-3 is smaller than that of the measurement method 4-6. Under the 95% trust interval, the population average error of measurement method 2 is the lowest; the error distribution of measurement method 6 is the most concentrated in area measurement.