This is very dangerous, first rule out is not the original mobile phone charger, because now many people will mix the charger, after ruling out this problem, just look at how long your mobile phone has been used, with a long time, there will be interface aging and loose phenomenon, there will be this problem when charging. Another is that your phone has changed the battery, the battery is not original, the temperature is too high when charging, and the heat will make you smell burnt. This is very dangerous, it is recommended to send to the repair check, either change the charger, or change the phone.