The invention relates to a data processing method which can read automobile HID electron ballast error message. The method includes error message recording and error message reading steps. Said error message recording includes steps as follows: (1) signal sampling; (2) data processing; (3) error analysis; (4) analysing error code; (5) storaging error code; (6) entering error protection: electrical source output is closed and ballast working is in low power consumption state. Said error message reading includes steps as follows: (1) communication interrupt; (2) ballast receiving computer command; (3) reading EEPROM; (4) sending data. The method can increase maintain efficiency, and can analyse cause of difficulty that ballast is used in automobile. The method can provide first-hand data for improving ballast continuously, analysing cause of difficulty in automobile and solving scheme.