Abstract: The present invention relates to medical instruments, and particularly to an improved micro-blood-sample collection tube. The auto-suction quantitative micro-blood-sample collection tube of the present invention comprises a micro-blood-sample collection tube which opens at both ends and is of pass-through construction, and a compressible air bag which opens at one end and is hollow. Said micro-blood-sample collection tube is made of hydrophilic material. One end of the micro-blood-sample collection tube is inserted and secured in a port of the air bag, and the inner cavity of the micro-blood-sample collection tube is communicated with the inner cavity of the air bag. The wall of the air bag is provided with a ventilation hole leading to the inner cavity of said air bag. The present invention does not need hydrophilic treatment, has low cost, highly marketable, and greatly increases the accuracy and efficiency of the blood-sampling process.