Objective To observe the area of the equivalent stress distribution and the maximum equivalent stress of the implant with the same diameter and different length of the implant combination. Methods SolidWorks software was used to establish three-dimensional models of implant fixed bridges with different lengths (group A: 4.1 mm×10 mm and 4.8 mm×10 mm; group B: 4.1 mm×10 mm and 4.8 mm×8 mm; group C: 4.1 mm×12 mm and 4.8 mm×10 mm; group D: 4.1 mm×12 mm and 4.8 mm×8 mm). The implant was placed at the lower right 5 and lower right 7. The diameter of the lower right 5 implant was 4.1 mm, and the diameter of the lower right 7 implant was 4.8 mm. The length was 8 mm, 10 mm, and 12 mm, respectively. The force of 100 N in the axial direction and 45° 100 N in the oblique direction was applied to the different implant fixed bridge repair models to observe the maximum equivalent stress distribution position and size of the implants in different models. Results Under the loading of axial and oblique 45° force, the maximum equivalent stress of the implant was distributed in the neck of the implant. When the vertical force was loaded, the maximum equivalent stress value of the right lower 7 in group C and group D was smaller than that in group A and group B; the maximum equivalent stress value of the lower right 5 was close; when the inclined force was loaded, the maximum equivalent stress values of the lower right 5 of group A, B and C were close, and group D was slightly larger than the other three groups; the maximum equivalent stress value of the right lower 7 was close to that of group A and group C, and that of group B and group D was close. Conclusion In the repair of implant fixed bridge, the change of implant length will have a certain influence on the stress value of implant, but the change is not significant. Based on this, it is advocated in clinical practice that the mesial and distal implants can be selected with a longer length and as close as possible, while the free end cantilever structure should appropriately reduce the mesial and distal diameters and buccolingual diameters.