A two-hot-boat chemical vapor deposition system was modified from a thermal evaporation equipment. This system has the advantage of high vacuum, rapid heating rate and temperature separately controlled boats for the source and samples. These are in favor of synthesizing compound semiconducting nano-materials. By the system, we have synthesized high-quality wurtzite single crystal GaN nanowires and nanotip triangle pyramids via an in-situ doping indium surfactant technique on Si and 3C-SiC epilayer/Si substrates. The products were analyzed by x-ray diffraction, field emission scanning electron microscopy, high-resolution transmission electron microscopy, energy-dispersive x-ray spectroscopy, and photoluminescence measurements. The GaN nanotip triangle pyramids, synthesized with this novel method, have potential application in electronic/ photonic devices for field-emission and laser.