An infrared lamp brightness adjusting method for an infrared camera, characterized by comprising: after an infrared lamp of the infrared camera is opened, performing processing as follows in each preset time period: determining whether a gain value of a surveillance image is in a gain interval; when the gain value of the surveillance image is not in the gain interval, calculating a viewing angle α according to a current magnification Z of the surveillance image, α = π 180 × θ Z, wherein θ is a maximum horizontal viewing angle of the infrared camera; respectively comparing α with β 3, β 2 and β 1, adjusting brightness of the infrared lamp according to a comparison result until the gain value of the surveillance image is adjusted into the gain interval; when the gain value of the surveillance image is in the gain interval, determining whether there is at least one sub-region with abnormal brightness in N sub-regions in the surveillance image, the N sub-regions having a same size with each other, N being a positive integer greater than 1; if yes, determining an infrared lamp adjustment mode through the viewing angle, α, of the surveillance image, and adjusting the brightness of the infrared lamp according to the determined infrared lamp adjustment mode until the at least one sub-region with the abnormal brightness returns to normal; wherein the infrared lamp of the infrared camera includes a near lamp, a middle lamp and a far lamp; wherein β 3 is an illumination angle of the far lamp, β 2 is an illumination angle of the middle lamp, β 1 is an illumination angle of the near lamp; wherein the far lamp, middle lamp and near lamp have different illumination angles, and β 1 > β 2 > β 3; wherein determining whether there is at least one sub-region with abnormal brightness comprises: for each sub-region, obtaining a theoretical brightness value and an actual brightness value of the sub-region, calculating an absolute value of a difference between the theoretical brightness value and the actual brightness value, and determining that the sub-region is a sub-region with the abnormal brightness if the absolute value is more than a preset threshold. determining whether a gain value of a surveillance image is in a gain interval; when the gain value of the surveillance image is not in the gain interval, calculating a viewing angle α according to a current magnification Z of the surveillance image, α = π 180 × θ Z, wherein θ is a maximum horizontal viewing angle of the infrared camera; respectively comparing α with β 3, β 2 and β 1, adjusting brightness of the infrared lamp according to a comparison result until the gain value of the surveillance image is adjusted into the gain interval; when the gain value of the surveillance image is in the gain interval, determining whether there is at least one sub-region with abnormal brightness in N sub-regions in the surveillance image, the N sub-regions having a same size with each other, N being a positive integer greater than 1; if yes, determining an infrared lamp adjustment mode through the viewing angle, α, of the surveillance image, and adjusting the brightness of the infrared lamp according to the determined infrared lamp adjustment mode until the at least one sub-region with the abnormal brightness returns to normal; wherein the infrared lamp of the infrared camera includes a near lamp, a middle lamp and a far lamp; wherein β 3 is an illumination angle of the far lamp, β 2 is an illumination angle of the middle lamp, β 1 is an illumination angle of the near lamp; wherein the far lamp, middle lamp and near lamp have different illumination angles, and β 1 > β 2 > β 3; wherein determining whether there is at least one sub-region with abnormal brightness comprises: for each sub-region, obtaining a theoretical brightness value and an actual brightness value of the sub-region, calculating an absolute value of a difference between the theoretical brightness value and the actual brightness value, and determining that the sub-region is a sub-region with the abnormal brightness if the absolute value is more than a preset threshold.