  Layered SnAs-based Zintl compounds exhibit a distinctive electronic
structure, igniting extensive research efforts in areas of superconductivity,
topological insulators and quantum magnetism. In this paper, we systematically
investigate the crystal structures and electronic properties of the Zintl
compound SrSn2As2 under high-pressure. At approximately 20.8 GPa,
pressure-induced superconductivity is observed in SrSn2As2 with a
characteristic dome-like evolution of Tc. Theoretical calculations together
with high pressure synchrotron X-ray diffraction and Raman spectroscopy have
identified that SrSn2As2 undergoes a structural transformation from a trigonal
to a monoclinic structure. Beyond 28.3 GPa, the superconducting transition
temperature is suppressed due to a reduction of the density of state at the
Fermi level. The discovery of pressure-induced superconductivity, accompanied
by structural transitions in SrSn2As2, greatly expands the physical properties
of layered SnAs-based compounds and provides a new ground states upon
compression.
