Titanium alloy investment precision castings have complex structures, are often thin-wall and have large cavities. Some rotational parts have large cavities and small openings. When making wax pattern die, conventional parting method is quite difficult, the wax die striping structure is complicated, the wax pattern die design and manufacturing are difficult and the diecost is high. In order to meet the needs of mass production, water-soluble wax core is used to make wax pattern with complex and fine structure. The results show that the dimensional accuracy of wax pattern is significantly improved, reaching CT3, and the surface roughness is ≤3.2 μm. There is no need to repair the inner cavity of wax pattern, and the production efficiency of wax pattern is nearly doubled. The internal and external defects of castings produced by the new technology are reduced by 70%, the cost is reduced, and the production efficiency and the quality stability of the castings are improved.