The surface morphology and electronic structure of layered semiconductor 1-trigonal phase titanium disulfide, i.e., 1T-TiS2(0001), with Sn intercalation, have been studied by scanning tunneling microscopy (STM), low-energy electron diffraction, synchrotron radiation photoemission spectroscopy, and first-principles calculations based on density functional theory (DFT). From the STM images, we show that Sn atoms are intercalated into TiS2 layers. The electronic structure exhibits electron Fermi pockets around M points and characteristic band dispersions around the M and K points after Sn intercalation. The DFT calculations reveal the geometrical site of intercalated Sn atom, which is surrounded by six sulfur atoms with D-3d symmetry. The calculated electronic band structures are in good agreement with the experimental band structure.