Abstract: As the FOAK, HPR1000 is required to carry out the in-reactor measurement of flow induced vibration of reactor internals based on the regulation Comprehensive Vibration Assessment Program for Reactor Internals during Pre-operational and Start-up Testing (RG1.20) . The evaluation shows that this will result in additional 2.7 mouths in the construction period in the critical path. In order to eliminate the effect of test-related work on the construction period, this paper proposes a feasible optimization scheme by analyzing the influencing factors, countermeasures, risks and the associated effects after taking these measures. The analysis results indicate that the effect of test-related work on the construction period (62 months) of FOAK project can be eliminated by adjusting the logic of critical path and duration optimization.