The present invention relates to a method for improving the germline transmission efficiency of avian primordial germ cells (PGCs), and methods for producing avian chimeras and transgenic using it. The present method comprises the steps of (a) isolating primordial germ cells (PGCs) from an avian embryonic gonad; and (b) culturing said PGCs in vitro for at least 5 days. According to the present method, the germline transmission efficiency of PGCs can be dramatically improved in a feasible manner.