An illuminating device comprises a heat dissipating module, a light emitting module arranged on the heat dissipating module, and a holder connected to the heat dissipating module. The heat dissipating module comprises a heat conductive plate and a plurality of fins; the heat conductive plate has a first surface and a second surface opposite to the first surface; the plurality of fins are configured on the first surface and extends along a direction away from the second surface. The light emitting module comprises a base attached to the second surface of the heat dissipating module and a light source; the base has a supporting surface and the light source is arranged on the supporting surface. A distance between the supporting surface and the second surface gradually increases along a direction from one side of the heat conductive plate to the other.