The invention relates to a distance protection method suitable for a same-tower four-circuit line cross-voltage-class cross-line fault. The method comprises the following steps: acquiring the voltageand current in each phase of each circuit line in a same-tower mixed-voltage four-circuit line; determining a faulted line and a faulted phase in the same-tower mixed-voltage four-circuit line by aphase selection component; calculating the fault interphase cross-voltage-class cross-line impedance, and determining the positive sequence impedance used for protection setting; determining a distance protection setting value, and determining a distance protection operation logic by comparing the calculated the cross-voltage-class cross-line impedance with the distance protection setting value.