The utility model provides an in reentrant corner (1) of building wall exempts from to plaster in same direction as straight negative and positive corner structure, at the building and an outer anti split putty layer (6) have been scraped at reentrant corner strip (4) and external corner strip (5) exterior coating in external corner strip (5) that outside external corner (2), scrape on anti on the wall split putty layer (3) scribbling, pasting the angle respectively, to install the cross section be the L type for reentrant corner strip (4) and the cross section of L type. The utility model discloses can effectively solve house reentrant corner, the external corner straight not upright or quality problems such as the external corner is damaged, reentrant corner fracture that have some setbacks.