  As an intermediate state in the topological phase diagram, Dirac semimetals
are of particular interest as a platform for studying topological phase
transitions under external modulations. Despite a growing theoretical interest
in this topic, it remains a substantial challenge to experimentally tune the
system across topological phase transitions. Here, we investigate the Fermi
surface evolution of Cd3As2 under high pressure through magnetotransport. A
sudden change in Berry phase occurs at 1.3 GPa along with the unanticipated
shrinkage of the Fermi surface, which occurs well below the structure
transition point (~2.5 GPa). High pressure X-ray diffraction also reveals an
anisotropic compression of the Cd3As2 lattice around a similar pressure.
Corroborated by the first-principles calculations we show that an axial
compression will shift the Dirac nodes towards the Brillouin zone center and
eventually introduces a finite energy gap. The ability to tune the node
position, a vital parameter of Dirac semimetals, can have dramatic impacts on
the corresponding topological properties such as the Fermi arc surface states
and the chiral anomaly. Our study demonstrates axial compression as an
efficient approach for manipulating the band topology and exploring the
critical phenomena near the topological phase transition in Cd3As2.
