This paper analyzes in detail Gulfstream G650 flight test accident from the management and technical problems based on the investigation report by flight test engineers. Firstly, the key events and their logic connection about the accident were presented, and then the causes were separated by management and technical categories. For management issues, the test procedure, test plan, risk management were reviewed. The faulty stall warning Sangle of attack setting was analyzed based on ground effect model and test data. The low takeoff safety speed was illustrated by comparing the takeoff speed flight test procedures. At last, some suggestions on flight safety were presented.