A mobile device for detecting and marking blood vessels is provided, which comprises: an ultrasonic transmitter configured to transmit an ultrasonic wave； an ultrasonic receiver configured to receive the ultrasonic wave reflected by the skin and soft tissue of a patient； a marking unit configured to execute a marking action； and a processor configured to analyze the ultrasonic wave reflected by the skin and soft tissue of the patient to determine whether a blood vessel exists under a contact position between the mobile device and the skin and soft tissue of the patient. When the processor determines that the blood vessel exists under the contact position, the processor controls the marking unit to execute the marking action to mark a position of the blood vessel. A corresponding method for detecting and marking blood vessels is also provided.本發明提供一種用於血管偵測及標示的行動裝置，包括：一超音波發射器，用於發射一超音波；一超音波接收器，用於接收一患者的皮膚與軟組織所反射的該超音波；一標示單元，用於執行一標示動作；以及一處理器，用於分析該患者的皮膚與軟組織所反射的該超音波，以判斷該行動裝置和該患者的皮膚與軟組織的接觸位置下方是否有血管，當該處理器判斷該接觸位置下方有血管，則控制該標示單元執行該標示動作以標示該血管的位置。本發明還提供一種相對應的血管偵測及標示方法。
