Based on the subgrade project of Jiyuan-Xin’an Expressway, a field test of compaction and reinforcement of high-fill loess embankment was designed and conducted, the reinforcement effects and influence depth of two reinforcement schemes, namely dynamic compaction and impact rolling, were discussed, and the finite element method was used to further optimize the construction parameters for the impact rolling scheme with better field reinforcement effect. The results show that the influence depth of dynamic compaction reinforcement ranges from 4 to 6 m, while that of impact rolling reinforcement ranges from 2 to 4 m. Within the influence depth range, the reinforcement effect of soil improves with an increase in dynamic compaction or rolling times, but the increase gradually decreases, indicating an optimal dynamic compaction or rolling time. According to the construction parameters of the in-situ test, impact rolling reinforcement after a 2-m fill height is more effective in improving the compaction degree and uniformity of the subgrade compared to dynamic compaction reinforcement after a 4-m fill height. The influence depth of impact rolling reinforcement increases with the rolling time, reaching up to 3 m after 20 times. Both the compaction effect and influence depth increase with the mass of the impact wheel but first increase and then decrease with an increase in the traveling speed of the impact wheel. The optimal traveling speed of the impact wheel is 3 m/s.