Different textures are formed in different thickness zones of CR340 tailor rolled blank (TRB) during rolling, including {111}<01> and {141}<22> textures in the thin zone, {225}<10> and {211}<01> textures in the transition zone, and {876}<5> and {411}<01> textures in the thick zone. The polycrystalline plastic finite element model in different thickness zones was established based on the results of EBSD test to study the influence of grain structure in different thickness zones on the activation of slip system and stress-strain distribution under uniaxial tension. The results show that the {111}<01> texture of thin zone and {876} <5> texture of thick zone are conducive to slip system activation, and 8 and 9 sets of slip systems are activated, respectively, which weaken stress concentration of equal thickness zone in the deformation process, so equal thickness zone has good plastic deformation behavior. However, the grain slip system of {225}<10> and {211}<01> textures in transition zone is less activated, and the number of activation is just 6 and 7, respectively, which lead to the high stress concentration, and thus the plastic deformation behavior is poor. The TRB presents obvious non-uniformity in plastic deformation because of the difference in texture of each thickness region, and the fracture position of the TRB appears in the transition zone with poor plastic deformation during uniaxial tension.