Tests of supply voltages and load resistances on several PTB220 pressure sensors are carried out for the accuracy and reliability of verification results. The test results show that the measurement errors of pressure sensor analog output are increasing gradually with the increasing supply voltage in the range of 12 to 30 V. The maximum error variation is up to －028 hPa, while there is no effect for digital outputs. The analog measurement errors of the PTB220 pressure sensors are increasing with the increasing of load resistance at the low limit of pressure measurement range for load resistance variation between 10 kΩ and 500 kΩ. Based on this finding, suggestions for the modification of verification method of PTB220 pressure sensors are proposed accordingly.