Temperature and humidity conducting gradient and segregation of materials, could cause obvious gradient deformation and terrible‐looking cracks on concrete surface. Because of the complicated cracking mechanism and numerous influencing factors, the prediction work of this cracks width in engineering is always very difficult. Combined with material segregation characteristics, the deformations of temperature change and shrinkage are considered by layers, and the inter stresses between layers are calculated out. After taking into account the crack toughness, the crack depth and width are determined. When the width exceeds 0.05 mm that is the recognized macro‐fracture index, visible crack of concrete is considered to occur. Using this method, the crack widths under several typical working conditions were calculated, and their distribution and development characteristics were analyzed.