Based on the engineering experience that subarea–scanning can effectively reduce the residual stress of large-scale structure formed by laser deposition forming, a finite element model based on thermo–elastic–plastic finite element theory was established to simulate the temperature and stress fields in the forming process. And the effects of different subarea–scanning on temperature and stress evolution, thermal cycling curve and residual stress of T–joint formed by laser deposition forming were studied. The results showed that the maximum values of thermal stress and residual stress occurred at the four outer corners of the contact between the upper edge strip and base metal, which is independent of the zoning method; The subarea–scanning has little effect on the outer corner points and the short outer midpoints of T–joint, but has certain influence on the thermal cycle curve and thermal stress curve of the inner corner points, the inner points and
the long outer midpoints; Subarea–scanning has a great influence on the distribution of residual stress, especially on the distribution law and amplitude of residual stress along the specified section.