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The experiment was to determine the effects of year, month and parity on the milk yield, milk protein rate, milk fat rate, urea nitrogen, persistence and somatic cell number of dairy cows. The 400 432 DHI data of dairy cows from 26 dairy farms in Shihezi City, Xinjiang from 2016 to 2022 were collected, and the DHI data of different years, months and parities were analyzed by SPSS 26 statistical software. The results showed that the milk yield in 2021 and 2022 was significantly higher than that in other years (P<0.05), the milk fat rate in 2019 and 2020 was significantly higher than that in other years (P<0.05), and the somatic cell number in 2016 was significantly higher than that in other years (P<0.05). The milk protein percentage from April to August was significantly lower than that in other months (P<0.05). The content of urea nitrogen in September was significantly higher than that in other months (P<0.05). The milk yield and somatic cell count in the second parity were significantly higher than those in other parities except the first parity (P<0.05). The milk yield, milk protein rate, milk fat rate and durability in the second to the fourth parities were relatively higher. The study indicates that the production performance of large-scale dairy farms in Northern Xinjiang (Shihezi City) is significantly related to the year, month and parity. It is of great significance to increase the proportion of cows in the second to the fourth parity and to rationally prepare the rations from April to August to improve the production performance, milk quality and economic benefit of the dairy cows. [ABSTRACT FROM AUTHOR]