Based on the data of well drilling, well logging, geological log and production test, combined with the core observation and thin section analysis, the hydrocarbon enrichment law and its main controlling factors of Chang 2 oil reservoir set in Xiasiwan Oilfield of Ordos Basin were studied. The result shows that the formation and enrichment of Chang 2 oil reservoir set are controlled by sedimentary facies, high quality reservoirs, nose-shaped uplift, fault, areal cap rock and migration pathway in Xiasiwan Oilfield, among which the nose-shaped uplift is the most favorable place for hydrocarbon enrichment. As migration pathways, fractures have significant effects on the formation and distribution of Chang 2 oil reservoir set. Lithologic reservoir and structural-lithologic reservoir are the main types of the Chang 2 oil reservoir set.