Abstract: 【Objective】 The content of fatty acids and the proportion of each component in oil crops are important standards to measure their oil use value, and it is of great significance to study the formation of fatty acids in oil crops. 【Methods】 Five different types of sunflower materials planted in different ecological areas were selected as the research objects. Through the determination of crude fat and fatty acid components, correlation and principal component analysis, the effects of different genotypes and ecological conditions on the fatty acid accumulation of sunflower were revealed. 【Result】 The results showed that the synthesis rate of total fatty acids in the early stage of embryo formation was higher, and the accumulation amount in the early stage could reach more than 20% of the total amount, while the accumulation amount in the later stage was generally within 15%, and the synthesis rate was significantly lower than that in the early stage. The synthesis rate of oleic acid has the same trend, except for individual varieties, the accumulation amount in the early stage can account for more than 30% of the total fatty acid, which is significantly higher than that in the later stage. The decrease of temperature in the later stage of seed maturity resulted in the decrease of the accumulation rate of oleic acid in seed. 【Conclusion】 The total amount of final fatty acids in sunflower was closely related to the duration of the rapid growth of fatty acids during the development of seed embryo; The high oleic acid varieties kept high oleic acid synthesis rate in the later stage.