The invention discloses an expansible pulsating heat pipe, which comprises a pulsating heat pipe substrate of a long circular loop pipe. The pulsating heat pipe substrate is divided into a heating section, a heat insulation section and a cooling section from bottom to top; the upper part of the cooling section is provided with an expanding chamber connected through a connecting throat pipe; the diameter of the throat pipe is one tenth to one eighth of the pipe diameter of the pulsating heat pipe substrate; and the volume of the expanding chamber is one tenth to one eighth of that of the pulsating heat pipe substrate. The expansible pulsating heat pipe has the advantages of reducing startup temperature, improving heat transfer capacity, avoiding the phenomenon of easy balanced pressure between adjacent pipes of the pulsating heat pipe of the prior art and having good innovativeness and practicability.