A bio oil burner comprising: - an oil lance, at the end of which there is an oil nozzle with spray holes for feeding atomized oil to a furnace of a boiler, - a first cylinder coaxially surrounding the oil lance and together with the oil lance delimiting an annular primary air flow channel which ends at an outlet of the primary air flow channel, - a second cylinder coaxially surrounding the first cylinder and together with the first cylinder delimiting an annular secondary air flow channel which ends at an outlet of the secondary air flow channel, - a third cylinder coaxially surrounding the second cylinder and together with the second cylinder delimiting an annular tertiary air flow channel which ends at an outlet of the tertiary air flow channel, and - a primary air swirler annularly surrounding the oil nozzle and blocking at least part of the outlet of the primary air flow channel, wherein - the oil nozzle has a slanting circumferential surface and 6 - 50 spray holes which are distributed on the slanting circumferential surface of the oil nozzle in such a way that said spray holes form at least two groups (B1, B2) of spray holes in which the spray holes are located at a regular spacing from each other, and that between said groups (B1, B2) of spray holes there are intermediate spaces in which no spray holes are present, and the circumferential length of the intermediate spaces is greater than the circumferential spacing between the spray holes within the group (B1, B2), - the first cylinder has a free end at the outlet of the primary air flow channel, and the free end of the first cylinder is provided with a flame stabilizing ring surrounding the outlet of the primary air flow channel and blocking part of the outlet of the secondary air flow channel, and - the outer diameter D i of the primary air swirler is calculated by the formula D i = a • D 1ry, wherein a is 0.45 - 0.6 and D 1ry is the inner diameter of the first cylinder. - an oil lance, at the end of which there is an oil nozzle with spray holes for feeding atomized oil to a furnace of a boiler, - a first cylinder coaxially surrounding the oil lance and together with the oil lance delimiting an annular primary air flow channel which ends at an outlet of the primary air flow channel, - a second cylinder coaxially surrounding the first cylinder and together with the first cylinder delimiting an annular secondary air flow channel which ends at an outlet of the secondary air flow channel, - a third cylinder coaxially surrounding the second cylinder and together with the second cylinder delimiting an annular tertiary air flow channel which ends at an outlet of the tertiary air flow channel, and - a primary air swirler annularly surrounding the oil nozzle and blocking at least part of the outlet of the primary air flow channel, - the oil nozzle has a slanting circumferential surface and 6 - 50 spray holes which are distributed on the slanting circumferential surface of the oil nozzle in such a way that said spray holes form at least two groups (B1, B2) of spray holes in which the spray holes are located at a regular spacing from each other, and that between said groups (B1, B2) of spray holes there are intermediate spaces in which no spray holes are present, and the circumferential length of the intermediate spaces is greater than the circumferential spacing between the spray holes within the group (B1, B2), - the first cylinder has a free end at the outlet of the primary air flow channel, and the free end of the first cylinder is provided with a flame stabilizing ring surrounding the outlet of the primary air flow channel and blocking part of the outlet of the secondary air flow channel, and - the outer diameter D i of the primary air swirler is calculated by the formula D i = a • D 1ry, wherein a is 0.45 - 0.6 and D 1ry is the inner diameter of the first cylinder.