The invention relates to the field of underwater static sounding technology equipment, in particular to a transmission shaft and a drill rod retracting and releasing mechanism. The transmission shaftis of a hollow structure, a first transmission portion and a second transmission portion are arranged at the two ends of the transmission shaft correspondingly. A through hole allowing a signal transmission line to enter an inner cavity of the transmission shaft is formed in the outer peripheral surface of the transmission shaft. The first transmission portion and the second transmission portion are configured to cooperate with a transmission device so that the transmission shaft can be driven to rotate and move along the axis direction of the transmission shaft. The transmission shaft is simple in structure and convenient to use, can effectively avoid knotting of a guide line for transmitting data, effectively ensures the normal operation of the guide line, and further ensures the runningstability of an underwater static sounding test device.