A safety insulin pen needle for an insulin pen, comprising a needle hub and a needle tube assembly base arranged on the needle hub, a needle tube being arranged on the needle tube assembly base; the needle tube assembly base is arranged at the centre of one end of the needle hub, and an insulin pen assembly part matched with the insulin injection device is arranged at the other end of the needle hub; at least one protruding clamping column is also arranged on the outer side wall of the needle hub at an end close to the needle tube assembly base; the safety insulin pen needle also comprises a trigger protector sleeved outside the needle hub, the trigger protector is in a sleeve shape, two ends of the trigger protector are respectively an opening machine end and a patient end away from the machine end, a through hole for the needle tube to pass through is formed in the patient end, at least one guide groove matched with the clamping column on the needle hub is formed in the side wall of the trigger protector, the guide groove is at least provided with one initial fixing portion and one tail end fixing portion, the initial fixing portion is close to the patient end, and the tail end fixing portion is away from the patient end, the clamping column on the needle hub is embedded in the guide groove in the trigger protector to movably connect the needle hub and the trigger protector; when the clamping column is positioned at the initial fixing portion, the needle tube extends out of the trigger protector through the through hole; when the clamping column is positioned at the tail end fixing portion, the needle tube is positioned in the trigger protector; the safety insulin pen needle also comprises a spring, the spring is arranged between the needle hub and the trigger protector, and the direction of elastic force of the spring is the same as the axis direction of the trigger protector; and a downwardly extending lug boss is arranged inside the patient end of the trigger protector; the safety insulin pen needle being characterized in that it further comprises an annular cavity arranged between the needle tube assembly base and the outer side wall of the needle hub, one end of the spring is arranged in the annular cavity in the needle hub, and the other end of the spring is arranged on the lug boss inside the patient end of the trigger protector; the safety insulin pen needle being further characterized in that during the injection, when the needle tube is inserted into the human body, the top end of the trigger protector is in contact with the human body, and the spring is compressed to retract due to the acting force of the human body; meanwhile, the clamping column enters a first guide section from the initial fixing portion of the guide groove of the trigger protector, and interacts with the upper edge of the first guide section, so that the trigger protector rotates at a certain angle, until the clamping column is separated from the first guide section and enters the starting end of a transition section; when the needle tube is pulled out of the human body, the spring forces the trigger protector to move to the patient end and the clamping column, through a transition section, to the tail end fixing portion.