A time of flight (TOF) assembly includes a laser light source, one or more photo detectors and a detection circuit. The one or more photo detectors are configured to receive light and convert the received light into an electric signal. The detection circuit is configured to send a turning-off control signal to turn off the laser light source in response to the electric signal indicating that a time length, in which the laser light source is in an effective working state within a first duration, is greater than a preset time length threshold value or the electric signal indicating that energy of light emitted from the laser light source within a second duration is greater than a preset energy threshold. The disclosure also provides a terminal device and a control method for a TOF assembly.