Abstract ： Research purposes ： In order to research the different influence degree of newly - built tunnel approaching to existing building from different distance and different position，based on the stress state of the sharing rock between tunnel and building， the influence partitions of tunnel approaching to building would be established by numerical simulation method. On the basis of influence partitions，the countermeasure grading would be proposed. Research conclusions：( 1) Based on Mohr - Coulomb criterion，influence partitions as divided into strong，weak，and none influence zones can be divided according to the stress state of sharing rock after tunnel excavated as following three cases： 11 all yield， all in stress concentration state but not all in yield， some not in stress concentration or even in improved stress state compared with that before tunnel excavation11. (2) Specific to the calculation parameters in this paper，the influence partitions are divided as following ： at direction of 0 degree， strong influence zone is within 1.0d from existing building boundary， none influence zone is greater than 3. 0d; at direction of 30，45，60，90 degrees， strong influence zone is within 1.5! from existing building center，none influence zone is greater than 3. 0d. (3) For the influence partitions from strong to none mentioned above，countermeasure grading could be matched as 11 advanced reinforcement measures, only strengthen excavation parameters control，construct as usual . (4) The research results have certain guiding significance for fine management to projects of tunneling near the existing buildings.