The invention discloses a construction method of arbor tree ball island method soil in-situ improvement and restoration. The construction method includes the following steps of 1, arbor pruning; 2, arbor tension brace reinforcing; 3, reserving of a tree ball island; 4, digging of an improvement hole; 5, arrangement of annular drainage ditches; 6, arrangement of air-permeable observation pipes; 7, soil formula improvement; 8, improved soil backfilling. Stacked soil obtained in the step 4 of digging of the improvement hole is scarified, aired, subjected to impurity removal and broken, then an improvement medium is added in proportion, the materials are turned over and stirred to be uniform, and improved soil is obtained. The improved soil obtained in the step 7 is backfilled into the dug improvement hole, and the backfilled improved soil is layered and tamped. According to the method, arbor soil is improved and restored through in-situ soil improvement operation, the procedures of balling up, wrapping, hoisting, transporting, heeling-in and the like relevant to tree transplanting are omitted, the influence of improvement construction on original arbor is reduced, and the survival rate of improved arbor is increased.