In order to study the reliability of the flexible optoelectronic interconnect structure in practical engineering applications, a finite element model of the optoelectronic interconnect structure with optical fiber embedded in flexible substrate is established. According to the optical device standard Telcordia GR-468, thermal cycle is loaded. The solder joint stress, fiber stress and optocoupler efficiency is analyzed in the optoelectronic interconnect structure. The results show that the maximum equivalent stress of the solder joint and the optical fiber is in the safe range under the thermal-structure analysis. The maximum photoelectric coupling loss is 0.7 dB, which indicates that the effect of photoelectric transmission is not significant. It can be determined that the photoelectric interconnect structure in flexible printed circuit board can ensure the stability of photoelectric transmission under the load of thermal cycle.