Abstract: The GaN based semiconductor, as the third generation of semiconductors, has been the main focus for blue light emitting diodes. Its production abroad has been greatly expanded but has only just started in China. In fact, scientists and engineers have to solve many problems and difficulties related to GaN based materials growth, device structure design and optimization of device processing, including modification of the MOCVD equipment to satisfy the requirements of high quality mass production. This is a great opportunity and challenge to the scientists and engineers in China.