Binary hydrogen-rich compounds with H clathrate structures can serve as high-temperature superconductors under high pressures. Here, a novel ternary clathrate structure YCaH12 with space group Pm-3m is uncovered at high pressure using ab initio methods. It is predicted that YCaH12 can be stable above 180 GPa and decomposes into YH6 and CaH6 above 257 GPa. Our calculations show that YCaH12 is a potential high-temperature superconductor with T c of 230 K at 180 GPa owing to the strong electron-phonon coupling related to the optical phonon softening of H-cages. The pre-eminent pressure-induced superconductive behavior under attainable pressure is encouraging in the ternary hydrides.