A heat dissipating LED signal lamp emitting structure includes an isothermal board, a light emitting unit on the isothermal board, a heat conducting cylinder connected to the bottom of the isothermal board, a heat dissipating body around the periphery of the heat conducting cylinder and comprised of heat sinks, a circular cover body above the isothermal board for covering the isothermal board, a reflecting groove at the center of the cover body for passing through the light emitting unit, and a transparent lid on the cover body for covering the light emitting unit. With the heat dissipating effect of the heat dissipating body, the operating heat produced by the light emitting unit can be dissipated to the outside. The invention not only uses a single light emitting unit as a signal lamp emitting source, but also enhances the light emitting efficiency and the life expectancy of the light emitting unit.