A terminal and electrical water-resistance method, the terminal includes: a circuit board, a battery providing a power source for the circuit board, a housing provided with a transparent medium used for reflecting light; the circuit board includes: a detection module, configured to: emit light towards the transparent medium, receive the light reflected by the transparent medium to convert into electric signal data to send to a control module; the control module, configured to: receive the electric signal data to compare with preset data, trigger the power-off switch when a difference value between the electric signal data and the preset data reaches a preset threshold which is preset according to the light and the transparent medium, wherein, the preset data are electric signal data when the light is totally reflected by the transparent medium; a power-off switch configured to: disconnect a connection between the circuit board and the battery after triggering.