The invention discloses a four-vertical-fin load loading method which comprises the following steps: 1) installing a vertical fin frame between inner vertical fins, connecting a single lug at the upper end of the vertical fin frame to a loading cross beam, and enabling the distance between the lower end of the vertical fin frame and a rear fuselage of an aircraft to be not less than 300mm; (2) theupper end of the vertical fin frame being connected with a loading cross beam through an upper end pull plate, and the lower end of the vertical fin frame being connected with a lateral loading standcolumn through a lower end pull plate; 3) installing an actuating cylinder fixing seat at a position corresponding to the vertical fin frame; 4) installing an actuating cylinder base at a position corresponding to the lateral loading cross beam of the vertical fins; 5) connecting the actuating cylinder with a loading cross beam by using a manual hoist, adjusting the actuating loading to meet therequirement by adjusting the manual hoist, and connecting the actuating cylinder with a vertical fin end lever; and (6) repeating the steps (2) to (5) to install the vertical fin loading equipment onthe other side. The four-vertical-fin load loading method can realize bidirectional tension and compression loading of vertical fin loads, and can avoid the spatial interference problem between the loading equipment and between the loading equipment and a test piece.