NP32-3646 is a three-interval and four-spud directional well with designed depth of 5798m. The swirl nozzle PDC bit was tested in the section of 3864m to 4265m (well deviation angle of 29.18 ), which had 5 drag blades with diameter of 16mm for its main cutters and 7 nozzles (3 ordinary ones and 4 swirl ones with 11mm and 18mm in diameter respectively). In deep and extra-deep well drilling, higher mud density and viscosity are usually employed, which is against to improve bit drilling efficiency. To address this issue, based on the produce mechanism and rock-breaking mechanism of swirling jet flow, the analysis is made on the field application of swirl nozzle PDC bit with 5 drag blades in well NP32-3646. The field application indicates that duo to its three-dimensional velocity of tangential, axial and radial, swirling jet flow can improve the cuttings removal performance at well bottom and rock-breaking can be realized by shear, erosion, stretching and grinding so as to improve drilling efficiency. The swirl nozzle bit obtained a total footage of 401m with average rate of penetration of 4.45m/h, which can meet the needs of field drilling and has good popularization and application prospect.