A delivery safety ensuring method for a wearable medical system, wherein the wearable medical system comprises a wearable medical device and an alternative physical key selected and inserted into the wearable medical device by a user, wherein the alternative physical key is carrying a proper operating mode configured to restrict a delivery amount within a pre-determined range, the method comprising the steps of: determining, via a processor, whether a delivery instruction given by a smart device is within the pre-determined range of the selected physical key by the wearable medical device; and, if the delivery instruction is within the pre-determined range, requiring, via the processor, for authentication of the delivery instruction or a suspension instruction from the smart device by the wearable medical device; receiving, from an authentication tool independent of the smart device, an authentication information by a receiver set in the wearable medical device, wherein the communication between the authentication tool and the receiver is a proximity communication without any direct physical contact being needed; and, if the requirement for authentication is satisfied, establishing, via the processor, a secure communication with the smart device by the wearable medical device; executing, by the wearable medical device, the instruction from the smart device; and instructing, via the processor, an alert system set in the wearable medical device to give a feedback to the user. the wearable medical system comprises a wearable medical device and an alternative physical key selected and inserted into the wearable medical device by a user, wherein the alternative physical key is carrying a proper operating mode configured to restrict a delivery amount within a pre-determined range, the method comprising the steps of: determining, via a processor, whether a delivery instruction given by a smart device is within the pre-determined range of the selected physical key by the wearable medical device; and, if the delivery instruction is within the pre-determined range, requiring, via the processor, for authentication of the delivery instruction or a suspension instruction from the smart device by the wearable medical device; receiving, from an authentication tool independent of the smart device, an authentication information by a receiver set in the wearable medical device, wherein the communication between the authentication tool and the receiver is a proximity communication without any direct physical contact being needed; and, if the requirement for authentication is satisfied, determining, via a processor, whether a delivery instruction given by a smart device is within the pre-determined range of the selected physical key by the wearable medical device; and, if the delivery instruction is within the pre-determined range, requiring, via the processor, for authentication of the delivery instruction or a suspension instruction from the smart device by the wearable medical device; receiving, from an authentication tool independent of the smart device, an authentication information by a receiver set in the wearable medical device, wherein the communication between the authentication tool and the receiver is a proximity communication without any direct physical contact being needed; and, if the requirement for authentication is satisfied, establishing, via the processor, a secure communication with the smart device by the wearable medical device; executing, by the wearable medical device, the instruction from the smart device; and instructing, via the processor, an alert system set in the wearable medical device to give a feedback to the user.