An illumination lamp comprises a lamp body, a light-emitting module, a power supply module, and a circuit module. The lamp body defines an inner space. The partitioning unit is disposed in the lamp body for dividing the inner space into a first space for receiving the power supply module, and a second space for receiving the circuit module. Due to the presence of the partitioning unit, thermal convection between the first and second spaces is prevented to reduce adverse influence of a high temperature of the circuit module on the power supply module.