Single-walled carbon nanotubes (SWNTs) have shown great potentials in various fields attributing to their unique structure-dependent properties, therefore, the structure-controlled preparation of SWNTs is a crucial issue for their advanced applications (e.g. carbon-based nanoelectronics) and has been a great challenge for about two decades. We developed a strategy to produce SWNTs with specific chirality by using tungsten-based intermetallic compound nanocrystals as catalysts. The characterization of catalyst structure is very important to reveal the growth mechanism of SWNTs. We used transmission electron microscopy (TEM) including high-resolution TEM, scanning TEM, as well as image simulation to probe the W₆Co₇ catalyst structure before and after the SWNT growth. In-situ TEM performed at 1100 ^oC was used to prove that the W₆Co₇ catalysts are crystalized and keep stable structure. High-resolution TEM measurements assisted with DFT simulations on the interface of SWNT/catalyst show that the chirality-specific growth is due to a good structural match between the nanotube and the metal atom arrangement of planes in the catalyst. The chirality characterization is also very important. We found that the electronic Raman scattering (ERS) can offer an accurate chirality assignment for metallic tubes. We also developed a bilayer plot for determining the chiralities of SWNTs under complex environment.