The temporal and spatial coherence of light emitting diode (LED) is studied by Michelson interferometer with subfemtosecond time resolution. LEDs′ spectral characteristics and coherence time are measured, and their emitting area is estimated by LEDs′ interference signal. Systematic errors in the experiments are discussed and the solutions to reduce the errors are suggested. Results show that LED can be applied as a light source for stable and time resolved spectroscopy.