The present invention relates to a visual inspection system for automotive piston assembly quality, which belongs to the technical field of automated optical inspection. The visual inspection system comprises a piston feeding mechanism, a piston discharging mechanism, a piston detection mechanism and a PLC (programmable logical controller) control module, the PLC control module is connected with the piston feeding mechanism and the piston discharging mechanism through communication lines of an I/O (input/output) port and is used for outputting control commands and receiving work piece in-place signals, and the piston detection mechanism is arranged between the piston feeding mechanism and the piston discharging mechanism and just faces to a piston to be detected, is also connected with the PLC control module and is used for transmitting detection information. The visual inspection system can realize one-step automatic visual inspection of characters on the top surface of the automotive piston, the assembly of a piston ring, the integrity of a graphite layer and the like based on digital images.