The invention provides a method for fast separating and extracting human Umbilical Cord mesenchymal stem cells (hUC-MSC) from umbilical cord outer layer amnion tissue. The method includes the following steps that fresh collected umbilical cord tissue of a healthy newborn is taken, transported on ice in double-antibody-containing umbilical cord storing transporting liquid, washed and disinfected with 75% ethyl alcohol and normal saline, outer layer amnions are separated bluntly after blood vessels are rejected, mechanically smashed and treated with erythrocyte lysate for 3 min, IV type collagenase digestion is used, and a digestion product is cultured in a suspension mode with a serum-free culture medium after being screened through a 100-200-mesh sieve; medium change is carried out every three to five days, supernatant is taken to detect cell contamination, after the attachment rate in a plate reaches 30-70% and trypsinization is used, cell passage amplification is collected centrifugally, and confluence is carried out when the cell confluence rate reaches 90% or above, the cells are collected for cryopreservation, and the biological characteristics of hUC-MSC are detected.