The invention discloses a regional power grid line forced power-on auxiliary decision making system which comprises a line information collecting module, a line information transmission module, a lineinformation identification module, a useless information removal module, a line information processing module, a line information decision-making module and a man-machine interaction interface display module. A regional power grid line forced power-on auxiliary decision-making method comprises the steps of s1, establishing a line information standing book, wherein the line information standing book comprises the full length of a line, stations connected, the line and cable relevant information, the short-circuit resistance of the main transformers of the stations connected and the short-circuit resistance of the main transformers which are in parallel operation with the main transformers of the stations connected, and other information including whether the line belongs to a line transformer group or not, and whether the line is a test operation line or not. The system and method are widely applied to accident treatment after tripping of a power grid line, and help a regional power grid dispatcher to decide whether to forcedly power on the tripped power grid line or not. If the forced power-on condition is met, a proper forced power-on terminal is recommended to the dispatcher, sothat the forced line power-on time can be remarkably shortened, and the forced line power-on efficiency can be improved.