Abstarct: Abstract Rapeseed Brassica napus L. is the second oil plant after soybean in the world, which accounts for 14.7% of the total vegetable oil production. The increase in population and the increase in the need to produce vegetable oils, as well as the increase in the area under rapeseed cultivation in recent years, have created favorable conditions for the activity of this plant's pests. Therefore, in order to produce more and healthier rapeseed, it is necessary to have a more detailed knowledge of the insects and pests of rapeseed fields in the country, so that by using this information, the management of rapeseed pests can be done correctly. For this purpose, in the present research, the insect fauna of rapeseed fields in a field located in Mazandaran province- Neka city and Ziaratkala village located in the heights of Hazarjarib in the crop year of 2020-2021 was investigated. The experiment was conducted in the form of a randomized complete block design with three replications and 10 treatments. The treatments included ten winter type canola cultivars including Opera, Akapi, 1008, 1009, Nafis, Ahmadi, Talaiyeh, Nilofer, SLMO46, KS7. The collection of insects using manual collection methods, insect nets and pit traps started in 7 stages with an interval of one week from April 16. The collected samples were taken to the laboratory. After separation and counting, it was transferred to 70% alcohol. In this study, 19 species of insects were collected during different stages of sampling. Most of the insects collected were from the hardy winged order. In this study, Margalef species richness index and Hill, Mackintosh, Shannon-Wiener and Simpson species diversity indices were calculated in the investigation of rapeseed insect biodiversity. The results showed that the highest indices of species richness and diversity were related to the Opera variety (Margaloff index equal to 2.08, Hill index 10.333, Mackintosh 0.573, Shannon Weiner 1.393 and Simpson index 0.680) which in sampling The third was obtained. Akapi, Nafis, KS7, 1009, 1008, Talaeei, Ahmadi, Nilo and slmo46 cultivars were in the next ranks. The highest species richness and diversity were obtained in the third and fourth sampling (at the time of late flowering and seed filling). Since most of the identified insects are rapeseed pests and beneficial insects were less observed in this study, it can be concluded that pests in the stages of flowering and podding are rich and diverse, and pest control and spraying with pesticides in this stage can reduce be damaged.