The present disclosure discloses a method, a terminal device and a system for controlling transmission, relating to the field of terminal technology. In the method for controlling transmission provided by the present embodiment, a user type of a current user is acquired, and when it is determined that the user type of the current user is the user type specified to reduce radiation, the terminal device reduced a default transmission power, thereby solves the problem of strong radiation generated by a terminal device in the prior art, which adopts a default transmission mechanism for optimal signal, and further achieves an effect of reducing radiation for the user types that need to reduce radiation.